Get help with an item purchased from the iTunes Store, App Store, Mac App Store, or iBooks Store - https://support.apple.com/HT204084
iTunes Store charges on credit and debit card statements - https://support.apple.com/HT201382 - "See an unfamiliar iTunes Store or App Store charge? Before you contact Apple, check your iTunes Store purchase history for more details."
Report a Problem - http://reportaproblem.apple.com - "Sign In for help with iTunes purchases made in the last 90 days"
Other ways to contact iTunes Store Support:
https://support.apple.com/contact
https://www.apple.com/emea/support/itunes/contact.html