First of all:
If he is egistered on MPGH, go to he Scammer Grave and report him there.
Then go on z8games and write a support ticket.
Go to support -> Crossfire -> Supmit a ticket.
Then choose Account Recovery or something like that and enter all the infomation you have got.
Like, PSC IDs, Paypal trananstions etc...
I just noticed the "Submit a ticket" page is down, so you will have to wait
Notice: Always use Middleman to trade! It is the safest way.
Good luck