If he has used your credit card without permission, it is totally wrong. It amounts to misuse and a form of cheating. Ask him to refund the money he used through your card. After that, write to the bank and get that card cancelled. Apply for a new card. I think that should solve the problem.
In extreme case, you can report to the police because unauthorised use of another person's card is a crime.
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How can some one use your credif card unless you have disclosed your security number given on the back of the card,. or you have handed over your card to some known person who has noted the card number and the security numbey and validity date and misused it, pay pal or e bay are note responsible for such irresponbsible action on your part