The following is a guideline on how to obtain a refund from the iTunes store for any app you have purchased.
This does not apply to movies or music as all sales are final.
One can request a credit from the iTunes store when the following applies
1) Application is corrupt.
2) Application does not perform as per description on iTunes
3) Application does not suit your geographic area ie Australia eg USA maps and no mention of this was in iTunes description
What you must do is Include your user name, your full details, the application name, the order number with date and the reason for requesting a credit
You will receive a response with in 48 hours then receive credit with in 5 days if it is a credit card purchase if you used an iTunes card I believe they issue credit to you account.
To locate your order number on your computer log in to your iTunes account, Account, recent purchases then look for the Application that you require a credit for. The order number and date is next to the Application name.
This links below will assist in contacting apple read this one first.
Troubleshooting applications purchased from the App Store
How to resume interrupted iTunes Store downloads
iTunesStoreSupport@apple.com. This is the email address to report your problem