Get banned for wrong reason form 3rd program

Today, i just log in to my account and it said that my account is banned and check my email. They said i used 3rd program as cheater. But i didn't use it on this account. The truth that i used 3rd on another account for skin changer and i get banned on it, but now i create a new one and it's clean. I just want Riot to check it and recover it back, cuz this is your mistake.