Guesser scammed me in a name change.

Profile link: http://www.sythe.org/members/466254-guesser.html
Explanation of the trade: I bought a RS account (for the name) from Sythe name: Guesser. The name was Prey, which is ironic, because that's exactly what I was to him. I spent 100m RS3 gp. The trade was carried out with a middleman (FlyingToast).
How they scammed: The trade was completed and I logged into the account and put 2 RS3 bonds onto it, planning to change it tomorrow morning. Before bed just now I tried to login to the account it did not accept my login details after several attempts (as shown in the screenshots). Upon trying to recover the account, I noticed that Guesser had changed the email from mine to his as I did not recognize the address: http://imgur.com/FXGAq4v
Skype profile: http://i.imgur.com/vkuIqaH.png
Skype conversation pictures (with MM): http://i.imgur.com/BlnUz5H.png , http://i.imgur.com/Q1xSLC7.png , http://i.imgur.com/1tfUI6P.png
Other images:
Proof that I logged in successfully and took a screenshot of name: http://i.imgur.com/rgIzudN.jpg

This might also help.
http://www.sythe.org/name-sales/1942481-selling-name.html

 

Banned (known name sniper/scammer)

http://www.sythe.org/report-scammer-archive/1902876-agony.html