How to find who else is billing my credit card from iTunes?

Apple support staff should only be able to see the transactions on your Apple ID once they are satisfied they are talking to you. It probably isn't possible for them to look up all transactions billed to a specific card, but even if it is that information would be confidential. The fraud department of your credit card company might be able to request that kind of detail, but not you.

Some more things to consider.

Review recent purchases at https://reportaproblem.apple.com/ or check your purchase history in iTunes and view your subscriptions. If you are the organizer of a family share check for purchases by other members.

See also If you see an unfamiliar iTunes Store or App Store charge on your bank, credit card, or debit statement - Apple Support and About payment card authorization holds in the iTunes Store - Apple Support.

If you cannot identify the payment then perhaps you are looking at a phishing email.

If there really have been purchases that you didn't authorize, or you've entered your Apple ID credentials at a fake Apple portal, see If you think your Apple ID has been compromised - Apple Support, change your Apple ID password, and if possible turn on Two-factor authentication for Apple ID - Apple Support.

See also Use Restrictions to prevent purchasing on your iPhone, iPad, or iPod touch - Apple Support.

• If there is no evidence of a charge on either your iTunes or bank/credit card accounts this is likely to be a phishing exercise which you should ignore.
  
• If there is a charge shown under your iTunes store account and it relates to misuse of your Apple ID then you need to start a conversation with iTunes Store support to get it cancelled and refunded, change your password, and enable two-factor authentication if at all possible.
  
• If it isn't connected to your own Apple ID but funds have gone from your bank or credit card account that purport to be from iTunes then the account has been compromised and you need to deal directly with your financial institution.

tt2

VladimirKai wrote:

...No one of us can remember that apple ID that was created and used that one time when I needed that file-transfer service and put my credit card into the form.

Ah, that would seem to be where the problem might lie. If you added your payment details into someone else's account you have no way to revoke them short of cancelling the card and getting a new one. They might not even be aware they are spending your money if they haven't checked their payment details again since. If you (or indeed anyone else) supplies the correct details associated with your card then Apple will assume they are dealing with the cardholder.

Of course if someone else does have your credit card information, and enough information to pose as you, the last thing that Apple should do is give them more information than they already have, which is likely why you cannot ask which Apple ID those mystery payments went to.

tt2