A bus passenger is being taken to court after an Oyster card reader failed to register her £1.20 fare.
Jo Cahill could face a £1,000 fine
Jo Cahill, 41, was confronted by an inspector on the 94 bus, telling her she had not paid and refused to let her pay in cash.
Two weeks ago she received a court summons for non-payment. She could be fined £1,000 if found guilty.
Transport for London said it could not discuss Ms Cahill's case because of the legal proceedings.
It added the Oyster card readers rarely fail.
Ms Cahill, a PA, told BBC News: "This is really heavy handed.
"I'm not a fare-dodger. The inspector just totally ignored me. I asked three or four times if I could pay the fare.
"He took my name, address and date of birth, confiscated my Oyster card. Then two weeks ago I received a court summons of non-payment of £1.20 bus fare."
Her case has been backed by the Capital Transport Campaign, which claims one in 20 Oyster card readers malfunction.
The group's spokeswoman Cynthia Hay said: "When the payment has been accepted then the red light turns green and there's a bleep.
"But if you are colour blind or if there's noise behind you then it can be hard to tell.
"Or if people are rushing to get in, it can be hard to tell. It's the same on the Tube."
Ms Cahill will appear before magistrates in November.