I've asked someone why I got banned and he said that i have modified my Halo 4 Achievements or something. (I think It's weird because I can see all of my achievements on Xbox Live and Halo Waypoint) When I got banned, I was trying to play War games in Split Screen with a friend and then got the ban message. (That's what I remember)
And there is a way to unban my console if i haven't done anything? :(As I said, console bans aren't handed out for no reason. To receive one you account will have been caught doing something it shouldn't have
Profile editing to unlock achievements that you didn't earn is a fast-track way to getting permanently banned. Good way of them seeing this is unlocking ones that can only be done online and they don't have a timestamp, indicating offline play.