Just to be clear they did give you a reason. So please stop this "I got ban for no reason" because they tell you right there in the note. With that said the 3rd party ban waves are for numerous things. Either you are lying and did in fact use scripts, or any other 3rd party program to help you in game. You paid for a service (like boosting) and said person used your account with the 3rd party programs. Or you were hacked and the person hacking you used scripts to get the account ban.
The two points warrants a punishment, the last is going to be hard to prove because you need to go back and see if any of the games in your match history aren't the games you played. If you can prove that you were hacked and someone got a hold of your account (without you giving it to them, or having a weak password) then they can help you and get you unban.