Why not use escrow? I wonder whether the user got compromised due to:
This user's email address was changed recently.
Additional Notes: Bought codes from him, first few times were good, he tried to get me to purchase all $4100 at once but I said I will buy 5 $100 he sent me his address, I sent him the bitcoin, he stopped replying, and now blocked me on Skype and called me a fucking idiot
May I know when the past trades were completed? If you do not want to give out any specific numbers, then give estimates (e.g. 1 week ago).