I Was Permanently Banned for No Reason

I really need help getting in contact with Riot and I'd appreciate any help I can get. I was notified that I've been permabanned for the "use of prohibited third-party software". I have never used any sort of cheat in my 4 years of playing this game, and I don't know what in the world Riot picked up to think that I was cheating. I had played a normal game this morning, and 1 ranked game before signing up with my friends for Clash, and during champ select is when I was notified that my account was banned. Please, if anyone could help me out in getting in contact with Riot in any way, I'd really appreciate it. I am positive I have done nothing to deserve this ban. Thank you.