Account breach punishment

I was playing last night till about 12:30 and put my computer to sleep and then went to bed myself, waking up to an e-mail saying I was banned for cheating. While i was asleep, my account was breached for the first time in my almost 5 years of having it. Someone decided to play on my account with cheats, getting me banned 2 hours after their last game. The previous ban i got on this account was a chat restriction last year, and im wondering why one game lead to a permanent ban while i was at honour 5, as well as why I wasn't notified from a different login, as i haven't used my account on a different computer than my home ones since last year. This person duo queued with the summoner M0N1 who I have never seen in my life and isn't on my friends list, and im just wondering why my ban was so severe, if the ban can be partially or fully lifted, and if its possible to have M0N1 punished for voluntarily queuing with a cheater.

(Edit) this guy also played champions i dont play often with much different stats than what I wouldve had - can this be used to help me appeal?