Be very careful
@tony888
I managed to do this today, BUT, only after an hour + on chat with MS. Basically, the rub of it was that after I applied Live gold to my account via VPN, I couldn't upgrade to ultimate afterwards ( after dropping off vpn and continuing to do the conversion). it kept on saying:
Change your Microsoft Store region
The region in which you bought your subscription and your Store region need to match. If changing your Store region doesn't work, contact us at Microsoft Support.
Change your Microsoft Store region The region in which you bought your subscription and your Store region need to match. If changing your Store region doesn't work, contact us at Microsoft Support.
The chat agent said that there are different types of prepaid codes available in the market so whenever you buy a prepaid subscription code, to make sure to purchase a global subscription code which is accessible in all countries. I eventually got escalated to another specialist, who tried to proces it on his end, no avail. They ended up removing the codes that I added to the acocunt, replacing it with new ones to the same date, and then I upgraded once they've removed and applied new ones.
I was stressing a lot during all of that, and not sure I can recommend it now.