PermaBan without, warnings, or ban whatsoever

Hello guys, my IGN is xis59 and I got recenlty banned for toxicty. Of course, I was kinda toxic, but not extreme toxicty (ex: Kill yourselves, racist things etc...). I am usually a not toxic player but in the last 2 weeks I gotta say I dropped a bit in my toxicty level and started flaming, but not in a really mean way. (Many times I was kidding and mentioned it in chat) So after one game I was a bit trollish toxic kinda, without anything too harsh, I got 5 premade reported and it got me perma banned. I never got any warnings, chat restrictions, 2 weeks bans in the last year at least. (Never got banned beside a chat restriction for like 10 games when it just came in the game and close to everyone had some most of the time) I sent a ticket to riot, they answered me with a bot automated text saying that I got warned multiples times and everything. I then wrote to them saying ive never gotten anything of the sort in a reallly really long time and they didn't answer. So if some of you have any solutions it would be reallly nice. I played with this account for more then 5 years and I never gotten anything like that before. Thanks everyone (english isnt my main lanugage sry)