banned for using 3rd party program again

Just like my last account. I never used any, any, any 3rd party program. And in the email, it says: malicious 3rd party programs or modifications to your League of Legends client. I didn't even use a record program or skin change. Last time, I contact riot game support, I asked the stuff to help me check out, what program or which part on the client has problem. What riot stuffs told me was they couldn't check anything. I really don't understand, I want to know what is happening. So, you say im cheating, but you can't tell what actually help me cheat. And when I am asking for help, you refuse to help. I have porb 300+ skins on this account and 200+ skins on my last account. And I was playing normal, aram, then I disconnected and got banned. Do you really have a accurate system to detect 3rd party program or you just ban who every got reported? Ok, I don't know if i really got reported by someone but this is what happened on my duo partner couple months ago. I was sup, and he was adc(ezreal), the enemy team has a lucian. At that time we were silver, cause my last acct was banned he used his unranked account to help me. That lucian Q, and my partner E away from his Q, almost every time, thats normal, easy move. My partner is a Diamond 1 adc main, thats so easy for him. But that lucian said in all chat, he said, my partner was cheating, that move, E away from his Q, in his mind should be impossible. And then he reported my partner, then! that account was banned for 3rd party program!!!!!!!!! And my friend contact game support, and riot asked for some data or something from him, but eventually, nothing report back. His Diamond 1 account is not banned. Anyone can explain?

For this time, I will still contact game support, to exonerate. Man I have 300+ skins on this account and 200+ skins on my last, I must be a idiot, cause riot said I used malicious 3rd party programs or modifications to my client! If i get my account unbanned, I will give it to someone, cause I once loved this game so much. I f i can't get it unbanned, I will just leave this game, no more, no trust. Overwatch, coming! league is a good game, but the support team, hum.