When we cancelled our card/account we tried claiming ours back saying we never requested it and hadn't realised we had been paying PPi, but the credit card company just told us that we'd ticked the box and, therefore, we had no claim. So we contacted one of these companies who claim on your behalf (for a fee, but we figured that without this company we wouldn't be getting anything back from PPi, so it's worth having to give them £140 to do it) and after one letter and phonecall our credit card company agreed to pay back all that we'd paid out.