Me and simple made deal (£69 for 700000 fifa 12 ultimate team coins) i paid him the coins which i could also prove but at the moment i'd rather see if i can get in contact with him then take more pics.
Do you have proof that that was indeed him you sent the money to (Ie, trade screen over the contract that displays his team name ''the blues'' or acknowledgement by him that he has received your coins?)
there is no way of proving that however i have noticed that he is now banned. Im more interested in why he didnt reply when i know that he has been online. out of interest do you ip ban as he could easily make another account?