Account permabanned because of someone else

I have been away from league of legends for quite a while now, I think it has been like 3 years since I last played this game, so I tried to log in today, and I got a message that said I was permabanned due to bad behaviour, the problem is...I didn't do anything, someone else that knew my password was using my account to play LoL and ended up getting me banned... I would like to know if there is any way I can get my account permaban raised, since I am not the one that caused all this trouble...I have spent a lot of cash on that account and I find it highly unfair... I hope someone from Riot sees this and decides to help me...Thanks!