Billing. What is this bill for? Offer HX8L8Q73M 12.98

We are fellow users here on these forums, we won't know. Where have you got that id and amount from e.g. if it's an emailed receipt then is it a genuine email from iTunes ?

You can view your iTunes account(s) purchase history via the your computer's iTunes : See your purchase history in the iTunes Store.

If it shows on your account an you don't recognise it (and nobody else has access to your account or devices and made it) then contact iTunes Support : http://reportaproblem.apple.com/