It's guaranteed credit, you are entitled to the goods you piad for or your money back. When buying something from a closing down sale you really MUST use a credit card.
Don't be fobbed off by the bank or card issuer, Master Card are a little better than Visa but in either case the law protects you. Contact the claims department ASAP.
Did you sign anything or use you PIN number? if you ordered by 'phone it's even easier to get out of paying ;) as the reciept should say "customer not present".