Does it show on the purchase history of any iTunes Account that you’ve linked to the card ? If it does, and if neither you nor anybody you’ve given access to the account did it, you should contact iTunes Support e.g. via your purchase history or the emailed receipt or the ‘contact support’ link at the top right of every page on here (obviously nobody on here can potentially refund you, you know that we are just fellow users). If it doesn’t show, and if it’s not a temporary store holding charge, contact the card issuer.