and im fairly certain your rep doesnt have anything to do with getting banned. its more so other players can see how others like you and all that.
i spoke with an xbox live moderator once (he tried to have me banned for acting up on call of duty 4. we had a team of like 4 people with the clan tag RPG and we team killed in s&d. some times you just needed a break from serious gaming ya know? lol) anyways after i talked him out of a temp. ban from live he told me that 11 complaints filed in one hour is an automatic 24 hour ban.