Rail passengers at a south-west London station have been overcharged after a communication room was flooded.
Some commuters at Clapham Junction station paid more than £20 a day as the system charged the maximum amount for their journeys.
One traveller criticised Transport for London (TfL), saying the barriers should have been left open to avoid people being overcharged.
TfL said the issue had been fixed and refunds were being issued.
Lloyd Tingley, 30, from Clapham, was left out of pocket by the error.
His usual rush-hour journey from Clapham Junction to Victoria normally costs about £7 a day, however when he received his charges for last Tuesday it was £12.80.
"I was a little bit confused but didn't really think anything more of it. Then I actually travelled to Waterloo on the Thursday and got my charge on the Friday and that was £23," he explained.
Mr Tingley said when he checked his account on TfL's website, it showed his journeys were incomplete so the system charged him the maximum fare.
He said TfL had "done nothing" to alert passengers to the fault, adding he had not seen it mentioned on TfL's X (the website formerly known as Twitter) feed and he had not seen any signage at the station to alert passengers.
"In my opinion they should just open the barriers and let people travel free of charge because I don't think it's fair that they are taking this money from people at all even if they intend to refund it," he said.
"It's unfair to be taking that money away from people in the first place especially in a cost of living crisis where some people really are budgeting hard and need that money.
"To have that taken away errantly - sometimes double, sometimes triple their fare - is just ridiculous."
Volkan Altinok, head of contact operations at TfL, apologised for the inconvenience.
He said: "Due to the communications room at Clapham Junction station being flooded last week, there have in recent days been issues where customers using pay as you go with contactless or Oyster may have been overcharged for their journeys if they entered or exited at the station.
"All customers who have been overcharged as a result of this will have these refunded and we are working with Network Rail and relevant train operating companies to ensure customers are aware of this issue."
In a statement, TfL added as Oyster and contactless cards would be automatically refunded, there was "no need" for customers to contact it to ask for a refund.