Current answers not exactly true (sorry!) so to clarify:
Whenever you buy anything your legal contract is with the seller, if there is a warranty from manufacturer you can try them, but that doesn't take away the seller's responsibility throughout.
The credit card company are just as liable to assist you as the seller is, this is covered in Section 75 of Consumer Credit Act 1974 and is called 'equal liability'. There are some factsheets on it on the net if you google it. It's nothing to do with any kind of insurance etc, it is the law and there isn't a time limit, just the usual 'reasonable' timescale when thinking about how long the item should have lasted for, up to max of 6 years.
If the seller is no longer there, then your credit card company seems your best bet, you may have to be persistent though, some are more helpful and willing to accept responsibility than others!