[LeeUmm]

In iTunes, when you're in the iTunes store, click on your email address in the top right corner to go into your account. Click the 'see all' for 'Purchase History' and then report a problem. If it's the last app you bought, click the button for it and then a link will display beside the price which you can click and fill out a form to ask for a refund.

[pinko]

Beware, however, that you can't do it often. I had a request for an expensive app refund denied because I had asked for (and been granted) a $0.99 app refund a few weeks earlier. So save it for when you need it.