Banned but I don't even played anymore

So today I got an email stating that I was banned for using 3rd party programs, ok fair enough. But the true mystery is that I don't even have LIVE server League installed as I quit a while ago and only use it twice to buy stuff off the merch store. The only person that know of my account information is my friend whom quit League a bit after I did and my other friend never seen me online since. I would just like someone from Riot to at least show me more evidence of this alleged use of 3rd party or whatever that got it banned. Thanks for reading!