Gave a trial period. Devalued my account(significantly changing things on it), keeps postponing payment and no longer responding to messages

Was trusted at first so gave him a trial period for the account. Didnt do anything wrong during that period and said he will take it off me and will pay asap when he gets the money. Almost a month later, no payment and proceeds to say a date on when he would receive money to pay me. I catch him buying an account on this site and proves that he could pay me but he hasn't. Significant changes on the account has been made during this time and confronted him about his recent purchase on here and is no longer responding to my messages. My account has been devalued.