1st ban, 1 week. 2nd ban, 1 month. And so higher on. But, if your first ban is a falseban, it goes your 2nd ban is 1 month but 1 week again. And it resets everytime you get falsebanned (not if you get falsebanned, and then hack). I've been banned like 3 times, all 3 times a falseban, and evertime I get unbanned within 2 hours after my appeal, and it resetted. So if he was falsebanned, he would've gotten unbanned already.
And revenge hacking isn't a reason you get unbanned, because it doesn't matter that someone else was hacking against you, you also ruined the experience for other players.
The rules state that you are not allowed to share you're account, because stuff like this can happen. And you got banned multiple times, so that means the one who 'hacked' your account, accesed your account multiple times, and you must've noticed that, cause you got banned, and see that on the screen. then the first time you contact the staff, so they know it, and you change your password, so the hacker cant get acces to your account again.