Wrongfully banned for use of 3rd party software ... please help

Hello everyone,

When I got home from work today I went directly to my computer as usual to play some LoL with my friends, but when I typed my credentials in the client I was surprised by an alert stating that my account was banned for use of third party software. The thing is I have never ever used such a thing on my computer, all I use from time to time is a vpn called mudfish to try to improve my ping and that's it. I never even play ranked, I'm pretty sure I played like 15 games ever on my account and none of it was from this season, so what would I use such a software on?? Can someone please help me and tell me what I can do to prove my innocence because I frankly don't know.

Thank you :(