I've just posted an answer to your other query about this - which was differently worded. It would be better if you could be clear about the situation before you post.
See my other answer - the bankrupt can get credit of �500 max. without declaring himself as such, but if he applied for a card without knowing what limit might be given then he may have committed an offence. He certainly would have done if the card limit had been more than �500 & he had not declared the bankruptcy.
It is most unusual to get a store card (or any other form of credit) while bankrupt. The store has probably made an error of judgement (or someone just didn't do the credit check properly) in issuing the card. Whether that is the case or not, the debtor is still liable to pay the debt.