I'm pretty certain that six months is the limit for card payments. That's what my bank told me a while back anyway. I had paid something by card and the amount was never debited. Also I hardly think a phone call is the correct way to deal with anything like this. It should have been put in writing. I would check with your bank just to be certain about the time limits. The burden of proof probably falls on the seller, but its always a good idea to keep all invoices and receipts, just in case. It should also still be possible to contact the card company and ask for a copy of your record, although they may charge for this.