Region locked gift.

My friend gifted me dlc for world war z. As usual i received a message on my xbox, which gave me the option to redeem there and then. When i tried to, it said sorry there was a problem, Download at Microsoft. I have done this before so it didnt seem unusual.
But it turns out it's region locked to the US. But she bought it through the gifting tab, she is uk based, as am i. She also was charged in £ sterling. But i we don't seem to be abke to get a refund, or just the code changed. No where has is stated in the
description, the email that also comes with a copy of the code, or on her end while purchasing that it would be region locked. Agaun, she purchased it using the xbix dash gift button. Any help her would be much appreciated

:)