Hacker gained access to my account through leak and got me banned

So lets start this by saying I was under a 14 day suspension as I was toxic from losing my promos and got banned. If I didn't have that then this wouldn't be a perma, but still, it's not really a fair ban.

So my account details were leaked on a popular cracking website about 10 days ago, and on the day of my 14 day suspension being over someone played a Vi jungle game on my Mordekaiser main account and flamed heavily and got me banned, I might have been toxic but not stupid enough that on the first game I'd do that. The image above shows me viewing my perma suspension chat log in disbelief as someone else logged onto my account and logged me out again. I messaged Riot support and was told password security is my responsibility (yes I understand that now, however getting banned from it isn't fair still). I gave Riot support all the evidence from my account being stolen and they just say it's my responsibility. Well in that case, everyone better be careful because everyday thousands of euw accounts are leaked on this forum, and you all deserve bans too clearly....

Riot should be able to look at it, see an unauthorised device and IP playing.