Your purchase could not be completed
How to fix this problem
If you are also getting a message to contact iTunes Support then that is what you need to do (these are user-to-user forums) :
- go to http://www.apple.com/support/itunes/ww
- click on your country's flag
- click on the Contact Support at the bottom of the left-hand column
- click on Contact iTunes Store Support on the right-hand side of the page