If you haven't already done so look at the purchase histories or all iTunes accounts linked to the card to see what you've bought : See your purchase history in the iTunes Store - Apple Support
If nothing shows could they be : About payment card authorisation holds in the iTunes Store - Apple Support
In terms of a refund purchases are considered, you would have to try contacting iTunes Support (e.g. via your purchase history) and see if they will refund you as a one-off