A man who was refunded over a £42 Watford to London return trip has warned other passengers to check their charges.

London Travelwatch has shared a warning today (May 8) over ‘device clashes’ which have led to passengers being overcharged.

It comes after a Freedom of Information Act (FOI) request from a member of public revealed that TfL is likely refunding more than £200,000 a year to passengers over the issue.

A 'device clash' is where a person taps in using one payment device, such as a phone, at the start of their journey but uses a different one, such as a bank card, at the end.

Paul Harper, of Cassiobury Drive, Watford, who made the FOI request, said: “I was stunned by how much was taken out of my bank in such a short space of time.

“One journey from Watford to London and back cost £42 which is ridiculous."

Watford Observer: Paul Harper.Paul Harper. (Image: Paul Harper)

The 42-year-old added: “In fairness, TfL refunded me very quickly within a week. But it did make me wonder how many other passengers are being overcharged without knowing, particularly people visiting the city for a day or weekend who probably pass it off as expensive travel.”

Even when two devices are linked to the same bank account, they have separate identity numbers for security reasons so TfL’s systems will think they are separate incomplete trips and therefore charge both the maximum fee.

London Travelwatch CEO Michael Roberts described the numbers as “startling” but suggested it could be “the tip of the iceberg” because it does not include passengers who do not realise they paid over the odds.

Watford Observer: Watford Junction sign.Watford Junction sign. (Image: Network Rail)

He called for banks, tech companies, and TfL to work together to find a permanent fix.

A TfL spokesperson said: “All customers using pay as you go are required to touch in and out using the same card or mobile device to ensure that they pay the correct fare and avoid incomplete journeys.

“This is particularly important when using mobile devices as each device is treated uniquely."

TfL highlighted that the estimated yearly total of refunds is less that 0.001 per cent of the £3billion in total contactless fares collected in a year.

“Where customers believe they have been overcharged, we are always happy to investigate and refund where we can," the spokesperson added.

“TfL will also look to automatically correct contactless journeys where we can based on previous journey patterns.”