app can't purchage, contact to support
your purchase could not be completed , for assistance, contact iTunes support at www.apple.com/support/itunes/ww/.
Have you done as instructed and gone to that URL and contacted iTunes Support ? If not you will need to do so (you already know that these are user-to-user forums, not iTunes Support) :
- go to http://www.apple.com/support/itunes/ww
- click on your country's flag (the country where you are, and which is therefore the country on your account)
- click on Contact Support towards the top right
- click on Get Help under 'Talk To Us'
Or use this form : https://www.apple.com/emea/support/itunes/contact.html