Its unfortunite that many untouched consoles have been banned, but as a standpoint against MS --- CALL BI_ATCH, WHINE and tell them to sent replacement console, and once they receive alot of untouched systems they will have to reconsider the BAN.
Buying a live card from another region will not get you banned, only issue is trying to activate cards as they are region specific so if your console and gamertag is NA, you will not be able to use a UK card, unless account/gamertag is a UK one.
I have come across a few people who only use live to donwload stuff, no mods, never touched, xmas presents and they got banned. They have contacted MS and they are awaiting replacement consoles. A theory maybe that swapped parts/refurbed units are being banned as well ( not original DVD drive ) and we know MS have a crap load of 3 red light systems.
Your account is still good,