Unfortunately SE won't change your account region, even if you actually move address into a different region. I don't know why.

I've also not heard of them swapping keys for different regions either so I'm afraid you're most likely out of luck there. You could try and get them to refund it, pointing out the key is unused, but I suspect they'll refuse and say all sales are final.

Regarding getting a new code, can you possibly ask the same friend to buy the game in their region for you to pass the code on? Not great I know and you'll have the same problem with the next expansion in ~2 years time, but it would work at least.

The alternative is buying a new base game/creating a new account/subscription and starting over (using your new HW code with that account), but I suspect you won't want to do that as looking at your character with 3 level 50s and 1 crafting levelled to 32 it's still going to take at least a month to get that all back if you play actively.

Sorry that I don't have a better reply