If you handed over you card and any passwords or PIN to another person then this is your own fault and it is unlikely that the bank will reimburse you. If your friend did use the card for in app purchases then potentially they may not have realized what they were committing to when they used your card to register. Regardless, your friend owes you the money back. If they don't then you could involve the Gardaí but if the amount is small (as in a few hundred) I would question how much they will get involved