does not in itself provide grounds for a claim against a supplier. In order to invoke section 75 you must have a valid claim of breach of contract or misrepresentation under another law, such as the Sale of Goods Act or the Misrepresentation Act. If you do, then you'll have a like claim against the card provider for the full amount of the claim.
As far as I'm aware there is not a one-year time limit on claims under section 75.
What to do next? The purchase was quite a while ago, but if you fancy providing some more detail I'll try to advise. Perhaps you can tell us about the problems your friend has experienced?