Banned for use of third party software

So today I tried to log in into my account via the client and a message appears saying my account is banned permanently for the use of third party software. I didnt know what it meant so I clicked on the site link. It says that I used an application or whatever what to help me win ranked games or normal games.. I dont even play ranked that much, I have like 30 games played. I play normal draft with friends most of it. So honestly I dont understand why I got banned for a reason I dont even understand.. I made a ticket to maybe get unbanned but it says that the decision wont be reversed unless theres a mistake. I created this discussion to maybe understand a little more that happened and if it happened to other people for no reason too and was a mistake indeed. Sorry for bad english ! Thank you