Hi, my apologies if I am posting in the wrong place, but I could really use some help.

I am sure that its something simple, but I've tried for two hours and now I'm desperate!

Just bought a card in Game to renew my Xbox live gold membership.
Redeemed the code on the xbox dashboard, and it asks for your details.
The problem is that I can only choose locations in america, so cannot proceed?
I have checked the xbox locale is set to UK, and really dont know what else to do?
I must have done something really obvious but I just cant see it.
Help would be greatly appreciated.
Thanks