banned for "3rd party software" i have never used

I came home late from work last night, to discover that my account has been banned for the use of third party software, i have played league of legends for few years now and have no idea how to even install 3rd party software. I am very upset by this false accusation and i am wondering how in the heck i am supposed to fix this and get my account back. I have filled out tickets to try and request it back, due to the fact I HAVE NEVER USED THIS SOFTWARE. very mad and i am in need of help. Please