Got banned with no reason

I got banned due to the use of malicious 3rd party programs or modifications to your League of Legends client, that was the reason of lol. I didnt use any cheat/programs/or anything, this frustrates me a lot since it is a unfair ban after I got all those skins/champs. I sended support a email but they dont want to investigate it deeper since I am one of the million players maybe. Can anyone help me, what can I do about it. I have been playing for 2-3 years and didnt do anything wrong.
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