You can view what you've bought yourself, you shouldn't need to talk to iTunes Support : See your purchase history in the App Store or iTunes Store - Apple Support
For a list of subscripitons : View, change, or cancel your subscriptions - Apple Support ; plus, if applicable, iCloud storage upgrade.
If you want to contact iTunes Support (obviously they can only help with purchases on your iTunes account, not, for example, if the credit/debit has been cloned, for that you would have to talk to the card issuer) : http://www.apple.com/support/itunes/ww