Who do we contact when we are double billed for 1 in app purchase?

I was double billed when an error appeared during an in app purchase and said the card would not be billed..... then I redid the in app purchase and it went through. Now I have two bills, but only 1 purchase registered in-app. I get an error stating my ipad cannot connect to the itunes store when I click the "report a problem" link on the receipt.

HELP!