At the heart of the dispute is the 10-day reduction in the time the bank allows to pay bills on many of its cards. This saves the Co-op substantial amounts of money. The move is being watched closely by other credit card operators, so all card customers should be on their guard against similar steps.
In February, the Co-op launched a new card, the Robert Owen Visa card. The main attraction was that it promised never to charge a fee. But people who wanted to avoid interest - by paying their whole bill in full - had only 15 days from their statement date to pay, instead of the 25 days under the Classic card. People who paid part of their bills would have 25 days to pay.
The Co-op decided to switch 100,000 Classic customers who regularly spent more than pounds 400 a month on their card to the new card.
The shorter payment period on Robert Owen is galling for customers who normally pay their bills in full - and benefit from the longer interest-free period. The bank insists that all 100,000 customers were warned about the change in writing and given the option of keeping their Classic cards.
A further 100,000 people with Co-operative Bank affinity cards have recently been switched to the Robert Owen card terms.
Spending on these cards benefits the Royal Society for the Protection of Birds, Help the Aged, the Labour Party and the Liberal Democrats.
Joan Warren, from Wallingford in Oxfordshire, is furious. 'To avoid interest charges, I have to pay in full within 15 days of the date of the account. That is not all. To pay by post, I have to allow seven working days.
'This month my account was dated 26 April, but did not arrive until Friday 30 April. I posted my cheque that day, but because of the Bank Holiday Monday it was not possible for me to meet the seven-working- day conditions.'
The Co-op says people who want to be sure they meet the 15-day deadline should pay by variable direct debit.Reuse content