quod te non occidit, te fortiorem faciet
The duration of a ban depends on the facts that you've done. It can be 15min, 2 weeks, a month, 3 months or even longer, like forever (correct me if I'm wrong). Normally, there will be a pop-up window in the game that will tell for how long you'll be banned.
If I'm not mistaken, and if you've been banned for too much quitting or betraying, it won't last too long, if it's your first time (much "ifs" huh ?).