Account Related Issue: Permabanned? Chat logs not my own, private account, steps?

Last Friday (8/19/2016), after 2 days of inactivity, I logged onto my account, CynicPlays, to find a permaban, and several toxic game chat logs, of which were not mine. In my last year of playing League, I have never been a toxic player, have never recieved chat restrictions, or temporary bans to suggest so. In fact, I hardly ever give a slight bm, and if I do, its 1 or 2 words per game, on rare occasion. This issue is quite frustrating, and honestly, I don't know how I should proceed. From what I've read, people don't get unbanned, and not being responsible makes this all the more irritating. At this point, I won't be making another account, so any help, suggestions, or advice is appreciated