Microsoft can be a big pain, especially with xbox 360's. Did you ever attempt to call them, and resolve the problem. There are a few ways that you can unban your xbox 360. But they are intensively hard, and involve flashing your 360's CPU Cache (Not easy) i have moded my 360, but only with hardware mods (Rapidfire, Blue ROL) but i couldn't help you with something like this, there are websites that you could look at.