Answer:
You should first directly contact the purchaser as they may have inadvertently given you the wrong credit card details and are not necessarily being intentionally fraudulent. If they do not respond to this request you may consider sending a letter of demand, if the debt is still not paid, you should consider taking the matter to court. Your Terms and Conditions should also set out the procedure as to what happens if payment is not received. You should seek legal advice as to what your best response is to the non-payment in your particular circumstances.