Unknown transactions

Look at the purchase histories of all iTunes accounts linked to the card : See your purchase history in the App Store or iTunes Store - Apple Support

If one or both don't show, and if one or both aren't just : About payment card authorization holds from the App Store or iTunes Store - Apple Support, contact the card issuer

Apple ID - If you see ‘itunes.com/bill‘ or an unfamiliar charge on your bank, credit card, or debit statement

If you've checked all iTunes accounts you have linked to the card see the rest of my reply