Neither my friend or I have ever been banned. We got the message on his console that both of our accounts, as well as the console, had been banned from earning credits. It pointed us to view the information at www.bungie.net/ban Bungie's website is very vague about the ban durations.
The duration of this ban will be based on the type, frequency or nature of the committed violation.
But nowhere do they list ban time frames by offense.
Types of violation include, but are not limited to, the following example actions:
Manipulating network conditions to give yourself an advantage, or to the detriment of the experience for other players.
Modifying your Xbox 360 hardware or Bungie software and services in any way.
Skill, EXP, or Credit Boosting, deleveling, idling through games, cheating, habitual quitting or any other type of unsociable and unsportsmanlike behavior.
Impersonating a Bungie employee on Xbox LIVE with intent to defraud or cause harm to other players.
I placed in bold the only reason they list that could have caused us to get banned.
It is our fault, although definitely not malicious. We left the game in the matchmaking lobby and my friends 4 year old son, having watched us for countless hours play, decided he wanted to. I'm guessing he was playing for about an hour before we came back to play, and he had gone through quite a few games getting betrayals.
I logged into my bungie account and also could not see anywhere on my profile where they would state any information regarding the ban or the time frame. It simply says "temporary" yet it has been 3 days now and the ban is still in place.