Irrespective of the method of payment, you have a right to a full refund on an item if it proves to be 'defective' (or, in your case, non-existent) before the point at which you've been deemed to have legally 'accepted' the product. With most purchases this period might only last a day or two but, obviously, you can't be deemed to have 'accepted' something which is non-existent. You therefore have the right to a full refund from the vendor.
If you're unable to obtain a refund from the vendor (e.g. because they've ceased trading), then you can make a claim against the credit card company under the terms of the Consumer Credit Act 1974. [Actually, you can go direct to the credit card company, if you so wish, rather than claiming against the vendor, irrespective of whether the vendor is still trading or not]. I'm fairly sure that Section 75 of the Act (which defines this right) does not specify a time limit. Assuming this to be the case, the usual time limit for claims will apply: i.e. you've got 6 years from the date when it first became apparent that the vendor was going to default on the agreement.
Remember, however that the provisions of the Consumer Credit Act only relate to credit card transactions (and not those made using debit cards) and also only apply to transactions between �100 and �30,000.
Chris