Robbin Banasiak took a cab from from San Francisco International Airport to her apartment in lower Pacific Heights and was charged $602.51 — 10 times more than the meter amount. She has been hassling with her credit card company over the fraudulent bill.

After a quick trip in a San Francisco taxi, the passenger handed a credit card to the driver to swipe, then hopped out of the cab.

Soon, a gargantuan charge — thousands of dollars — appeared on the passenger’s credit card bill for the ride. Despite months of pleading, the bank insisted the passenger owed the money and relented only after being contacted by a reporter.

Wait, you’ve heard this story before, right? The Chronicle’s article about Margarita Bekker’s $9,875 bill for an 11-minute Yellow Cab ride went viral earlier this year.

It turns out that Bekker wasn’t the only one with a supersize taxi fare in San Francisco.

Three people who read that story contacted The Chronicle to say that the exact same thing happened to them. Two of them, also in September, were charged by PayPal accounts using the same or very similar names as the PayPal account in the Bekker case. One was lucky: Her Discover card flagged the $7,800 fare for a 15-minute ride as fraud and never charged her.

The exorbitant taxi trips highlight some gaping holes in consumer protection, how social engineering can circumvent credit card protections and how consequences can be hard to come by. There’s also a clear moral for consumers: Always, always get a receipt.

The $9,980 fare: Tom Williamson, 73, flew from his home in Vancouver, British Columbia, to San Francisco in September for some gigs playing his trumpet around the Bay Area. He took BART from San Francisco International Airport to the Embarcadero, then hopped a cab for the short ride to his Union Square hotel.

The next morning he got a text alert from Wells Fargo that his credit card had been charged $9,980 the day before. “That was a bit of a shock,” he said. “I got in touch with Wells Fargo and said there must be some mistake; I clearly didn’t make this.” Wells told him it would cancel the card, send him a new one and turn the case over to fraud claims, he said.

He was on the road for a month playing gigs. When he returned home, Williamson found a letter from Wells saying his claim had been denied. “They said their technology showed the chip (on the card) was used, and that means it was in my possession and the purchase was obviously authorized,” he said.

Banks now embed computer chips in most credit cards for more security than magnetic strips. The riders who were overcharged discovered that this worked against them, as the banks insisted they must have authorized the charges because the chip had been read.

“The fact a chip was used has nothing to do with the fact that the amount was wrong,” said Lauren Saunders, associate director of the National Consumer Law Center. “That should be as plain as day. Banks can’t just rely on a standard response that their chip was used to avoid responsibility and correct errors and unauthorized charges.”

The Wells response kicked off a multi-month ordeal of Williamson calling and emailing the bank. He would speak to sympathetic representatives who agreed the charges didn’t sound right, but eventually he’d receive another letter — five in all — that his claim was denied.

He dug into savings to pay the bill. “I’m retired, on a fixed income, so that is a lot of money,” he said.

Finally, after stumbling across The Chronicle article on Bekker — whose San Francisco cab trip also cost almost $10,000 — he thought to himself, “That’s the smoking gun.”

He said his credit card bill showed the money was charged to the same PayPal account with a distinct name that showed up on Bekker’s credit card bill.

The Chronicle contacted Wells Fargo. Williamson soon received a call from a bank vice president, apologizing and saying he would receive an immediate refund.

“We regret that this process took too long and we understand the frustration our customer has experienced,” Wells said in a statement. “We are reviewing this scenario to determine how we can enhance our processes going forward.”

Banks should be more responsive to complaints about potential fraud, Saunders said.

“Clearly, these were errors; these cab rides did not cost $10,000,” she said.

Her tips for consumers: Get more attention by contacting the Consumer Financial Protection Bureau or the state attorney general, reaching out to local media, or tweeting to the bank.

The social engineering aspect: These cases illustrate a method that can thwart credit card chips: Giving a card to a merchant to swipe without the consumer seeing the terminal or receiving a receipt can open the door to fraud, while making the bank believe that a transaction was legitimate.

San Francisco cabs have a built-in card reader in the taxi’s backseat that is linked to the meter and cannot be overridden by the driver. But the San Francisco Municipal Transportation Agency allows drivers to use portable payment devices, such as those from Square or PayPal, because sometimes the drivers can get better deals on payment processing.

In all these cases, the drivers swiped the rider’s card on their own device, either PayPal or Square.

When Denise Lew, 52, an accountant, took a cab from downtown San Francisco to her Richmond District home in September, she handed her card to the driver and told him to add a $5 tip to the $23 fare.

A note from Robin Banasiak’s credit card company.

Discover card soon alerted her of a possible fraudulent charge of $7,800. She disputed the charge. Discover temporarily credited her, investigated and then after two billing cycles made the credit permanent, “much to my relief.”

She thought no more of it until she read about Bekker’s case, which prompted her to contact The Chronicle. Her bill showed that the $7,800 was charged to a PayPal account with almost the same unusual name as that used in Bekker’s and Williamson’s cases, but with the addition of the word “Taxi.”

These riders all made one key mistake: They didn’t insist on a receipt.

The SFMTA requires drivers to give receipts upon request. In October, it added a requirement for drivers using devices such as Square and PayPal to include their identity on the receipt, along with the fare, vehicle number, medallion number and their taxi ID number.

Drivers must give receipts, either paper or electronic, upon request. Taxi meters can print receipts for cash payments or when drivers use their own device to process payments.

The consequences for the alleged perpetrators: These outrageous charges also demonstrate the hurdles of collecting evidence and pursuing legal consequences.

The San Francisco District Attorney’s Office has looked into at least a couple of the instances. It does not comment on whether investigations are in progress or whether it plans to charge anyone.

Daniel Amador, an assistant D.A. in the special prosecution unit, said that fraud cases can be challenging to prosecute. For offenses such as embezzlement, false pretenses, access card fraud and forgery, it has to prove the defendants’ mental state and that they intended to defraud someone.

In general, the more victims, the better a chance a case stands in court. That underscores the importance of victims filing police reports or contacting the D.A.’s office, Amador said. Over time as the office compiles more instances, that provides the evidence it needs for a search warrant or arrest warrant, he said.

The D.A.’s office and the SFMTA both said that they have not received many reports of taxi overcharges, so they don’t think it’s a new kind of crime wave.

PayPal said it suspended the account of the driver with the unusual name that appeared in the September cases.

The SFMTA identified the driver in Bekker’s case and said he has not driven a San Francisco taxi since Oct. 1, 2021, without specifying whether his taxi license had been revoked.

That driver did not respond to emails from The Chronicle. The Chronicle is not naming the drivers because they have not been charged with crimes.

“Overcharging is prohibited by the Transportation Code,” the SFMTA said in a statement. “We will continue to investigate all complaints, including those related to overcharging, and we continue to work with our taxi industry stakeholders on proactive compliance.

The $602.51 ride: Robbin Banasiak, 29, took a 15-minute cab ride in November from SFO to her lower Pacific Heights apartment. She asked the driver to add a $10 tip on top of the $50 fare; he thanked her.

An hour later, she saw a $602.51 charge on her credit card statement. She called the issuer, Chase. “I spoke to a woman who said this is so outrageous, there’s no way you’re not winning this case,” she said.

But in December, Chase told her the charge was valid and she owed it.

She continued calling. “I’ve spoken to Chase many times and gotten every employee to agree that it was a ridiculous overcharge but they are refusing to give me the money back because the driver provided a receipt with the amount on it,” Banasiak said.

Robbin Banasiak looks over a note from her credit card company in her San Francisco apartment.

She never learned the driver’s name — the credit card charge was to a generic-sounding Square account. She asked Square for a receipt, which turned out to include the driver’s address. She sent three letters to that address without a reply.

She submitted complaints to the Consumer Financial Protection Bureau about both Chase and Square, but the agency closed them.

The taxi company owner and a San Francisco district attorney’s investigator told her they’d contacted the driver on her behalf asking him to refund her money — to no avail.

Chase and Square also reached out to him. Both Square and PayPal said that if a consumer contacts a credit card company before them, the bank becomes the final arbiter.

“I was hitting dead ends everywhere,” she said. “I don’t have enough money to be ripped off $600.”

After being contacted by The Chronicle, Chase refunded her money minus the original $60 fare.

“This is directly related to (The Chronicle) reaching out to them,” she said.

Williamson, the Vancouver visitor, had similar thoughts. The only reason he finally got a refund, he said, “is because the bank knew someone with more clout than me was looking at it ... saying, ‘Hey, we might shine a light on this despicable behavior.’”

And he owns his part in the debacle.

“Shame on me, that’s my lesson learned: always get a receipt.”

Carolyn Said is a San Francisco Chronicle staff writer. Email: csaid@sfchronicle.com Twitter: @csaid

Carolyn Said, an enterprise reporter for The San Francisco Chronicle, covers transformation: how society, business, culture, education and other institutions are changing. Her stories shed light on the human impact of sweeping trends. As a reporter at The Chronicle since 1997, she has also covered the on-demand industry, the foreclosure crisis, the dot-com rise and fall, the California energy crisis and the fallout from economic downturns.