The transaction happened without my knowledge and already went through. The only place where the transaction is shown is my bank account with the transaction titled "apple.com/bill, itunes.com" without any further information.
OK, looks like scam / phishing.
So you have not received an invoice from Apple.
Was the money deducted by a stranger?
Contact your bank, they can find out who (name, address & account number) has collected the amount from your bank account, and when.
Depending on your bank, they can collect the amount back within 30 days.
Ask also your bank to block your card, and ask a new card.
Also report to the police.
See also -> Identify legitimate emails from the App Store or iTunes Store
Identify legitimate emails from the App Store or iTunes Store - Apple Support