I made an in-app purchase, it failed, so I brought the full app

SO now I have been billed for both in-app and full app (same thing). All I want is a refund on the ip-app purchase, but the 'report a problem' link on the invoice is just going to:

http://www.apple.com/au/support/itunes/

How can I actually report the problem, without having to report a problem about the report a problem link.... total fail.