Banned for Third-Party Software

So I haven't been on good ole League since 2018 worlds happened because of Uni but when I got an email from Riot I checked and turns out I've been Permabanned. At first I thought it was a mistake because I almost always mute chat on the enemy team and if my teammates are trolling or flaming eachother I just mute them too so I've never really accosted anyone on my team of the enemy team enough to ever actually get banned temporarily so I'm left to assume that the reason why I was banned was due to third party software. The only known one I have is LOLreplay2 which I was comfortably using back in 2016 and all that so my only issue was if this was the reason why I was banned why wasn't I given a warning and secondly why is it ban worthy? I get riot doesn't really like to take back permabans especially if its to do with third party software but I really just want to at least have my skins or something from my old account because it was my baby and I had it back in 2012 so I'm petitioning anyone who there is anyway to convince riot to get me my account back.

Sincerely, SmilesCureAll