EXCLUSIVE: Several Australian customers of Budget Car Rental and financial giant American Express have been charged 100 times more than their bookings should have cost, due to a technical processing error.

Software engineer David Martin told Information Age that he awoke to a charge of almost $13,000 from Budget on his American Express credit card in mid-May – exactly 100 times the price of his booking with the car rental company.

Both American Express and Budget allegedly blamed each other for the error after being contacted by Martin.

An American Express representative told him that his overcharge was “a known issue” involving Budget, but Martin claimed a Budget representative told him an IT issue involving American Express had caused the error.

“It just seemed like everyone was blaming everyone, as per usual,” he said.

Information Age is aware of two other American Express and Budget customers who say they were also charged 100 times more than the cost of their bookings in May – both in the tens of thousands of dollars.

What caused the overcharges?

A decimal point error in “a transaction file” created by a third-party payment processor used by Budget’s parent company Avis Budget Group was to blame, an American Express spokesperson told Information Age.

"Some Amex Card Members who transacted with Avis Budget Group between 24 April and 11 May 2026 were charged incorrect amounts,” the spokesperson said.

“Upon identifying the issue, American Express acted promptly to correct affected customer accounts the following day.”

The spokesperson added that American Express had reversed “all associated interest, fees, and charges" and regretted “any inconvenience caused”, but would not confirm how many customers were impacted.

Avis Budget Group did not respond to a request for comment.

American Express previously told Martin that “incorrect transaction amounts were submitted” by Avis Budget Group’s payment processor.

The company admitted that his overcharging was “a significant transaction” and said it had “promptly corrected” the issue by reversing the charge the following day, in correspondence seen by Information Age.

It also apologised to Martin and said it would apply 20,000 reward points to his account.


American Express says the issue was caused by Avis Budget Group's third-party payment processor. Image: Shutterstock

Error made card temporarily unusable

Despite American Express allegedly assuring him he would not be denied use of his card after the error caused him to surpass his credit limit, Martin said his card stopped working during a business trip to Sydney.

"No lunch, and I got caught at the Circular Quay gates trying to get on the train to get to the airport – that was interesting in peak hour,” he said.

“... Then I got back onto Amex, saying, ‘I need my card, I need to be able to get food, I need to be able to get on the train, I need to be able to do things while I'm away in Sydney.’

“I advised them I was in Sydney, and they bounced me around to a few different places, and then essentially they just stopped helping.

“They just left it on read and didn't do anything – no response, no nothing in their chat.”

American Express acknowledged in an email to Martin that the overcharging “may have impacted” his ability to use his card.

“However, this was not the result of fraudulent activity by the merchant but rather a technical processing error, which was rectified as soon as it was identified,” the company told him.

Amex offers $450 to scrap formal complaint

After Martin filed a formal complaint against American Express with the Australian Financial Complaints Authority (AFCA), the company offered him a $450 credit if he signed a declaration “to finalise and resolve” the dispute.

Martin has so far declined to accept the offer to close his complaint, Information Age understands.

He also said Budget did not get back to him within 24 hours after he was overcharged, despite allegedly saying they would do so.

“It took, I think, four days to get back to me, and they pretty much offered no real apology or refund of the fee, or anything like that,” he said.

“In the end, I had to chase them, and they've only just offered $50 on the next rental.”

A spokesperson for consumer watchdog the ACCC (Australian Competition and Consumer Commission) said Australians who believe they were overcharged on a credit or debit card should “try to resolve the issue directly with the business in the first instance”, but can also contact their card issuer “about potential chargeback rights”.

“If consumers are unable to resolve their dispute with the business, they can check whether there is a relevant external dispute resolution scheme to apply to,” they said.

“For example, consumers who have hired vehicles from members of the Australian Finance Industry Association (AFIA) Car Rental Code of Practice can apply to AFIA to conciliate their dispute.

“If the above avenues do not resolve the dispute, consumers can report the issue to their local state or territory consumer protection regulator.”