We are fellow users here on these user-to-user forums, you're not talking to iTunes Support nor Apple.
Pre-orders aren't paid for at the time of ordering, they are only paid for when they are released and you download them - up until that point you could cancel the pre-order, so they can't be charged at pre-ordering.
Do you have an email receipt for the purchase and does it show on your account's purchase history ? Log into your account on your computer's iTunes via the Store > View Account menu option, you should then see a Purchase History section with a 'see all' link to the right of it, click on that and you should then see a list of your purchases.
If it does then does the Store > Check For Available Downloads menu option on your computer's iTunes download it, and/or does it show under the Purchased link under Quick Links on the right-hand side of the iTunes store homepage for downloading ?