Transport authorities have been slammed for knowingly overcharging some Oyster card users travelling from Wanstead and Woodford.

It has emerged that those who travel between Tube stops in Redbridge and stations on the opposite side of London via the Overground are charged for going through the more expensive Zone 1 central area, even when the journey avoids it.

Transport for London (TfL) has been made aware of the glitch but is not going to fix it until September at the earliest – because it only updates the Oyster system three times a year.

Anton Venter, 53, regularly travels between Snaresbrook Station and Ravenscourt Park in west London for his job as an engineer.

He has a travelcard which does not include Zone 1, so he avoids central London by using the Stratford to Richmond overground line.

But he is charged an extra £2.10p each time because the Oyster card pre-pay system wrongly assumes the journey goes through Zone 1.

He told the Guardian: “They know they are overcharging people but think they can get away with it.

“I first discovered it about three months ago but no-one has done anything about it since.”

TfL now automatically refunds Mr Venter every time he makes his journey, and told him at least one other passenger had also complained.

But Mr Venter said: “It's not the point that they are refunding me. What concerns me is that the vulnerable, like elderly people, are being ripped off but might not know about it.”

Mr Venter, who lives by the Eagle pub in Wanstead, also accused the publicly-funded London TravelWatch group of being reluctant to act and not investigating how widespread the problem could be.

A spokesman for London TravelWatch told the Guardian: “As Mr Venter’s complaint...has been resolved satisfactorily for him as an individual and he is being refunded each time he makes an affected journey, there is nothing more London TravelWatch can do.

“From time to time we do become aware of anomalies within the Oyster system like the one he has pointed out and we raise these with TfL, regardless of the number of passengers affected.

“However, they tend to affect a small number of passengers as they are unusual journeys.

“In an ideal world it would be good if TfL could fix these problems immediately but the fact is that it is quite expensive to upgrade the system and it is therefore in the wider passenger interest if they make the necessary changes as part of the upgrades they make three times a year.”

The Guardian is awaiting a comment from TfL.