ACCOUNT EMAIL

Hello fellow MPGH users. I'm facing a huge problem. I had purchased an account with only ID&PW about 10 months ago and it was kinda expensive.Till today i've purchased over 400$ and a lot of time spent on it. Problem is , few weeks ago i got a message from the guy that sold me the account that he would recover it if i don't send him an additional amount of money. I told him i don't have the money he's asking and he gave me a month to do so. I tried support tickets , with all the transaction ID's i've personally bought ZP through and the exact dates but these information don't seem enough. Is there any way to change the email besides support ticket and without having access into the email itself? I'd greatly appreciate it and i'm even willing to pay (a reasonable price) for a method that will work.
Hopefully someone can help me