All customer debit cards have been cancelled by the Abbey National's Internet bank Cahoot, following complaints that they cannot be used for cash withdrawals at supermarkets or to purchase goods in some shops.
All existing cards will become invalid on 30 September, Cahoot says it will start issuing working cards over the next couple of weeks.
The online bank, which also suffered computer failures on its launch day 12 June, says it was aware of the situation before launch and informed customers at this time. The bank also says it was not responsible for the error which it blames on Visa. "Visa issued the wrong type of card and we're having to sort it out," says a spokesman.
Visa acknowledges that the situation is its making and describes it as the result of a "one-off error caused by logistics".
Cahoot doesn't regard the blunder as a major concern and says customers haven't been seriously affected. "It was a frustration," admits a spokesman. "But it was something that we have known about for a while. We regard this as a fairly straightforward issue and do hope that it will be a seamless thing for customers."