Deception in trade

Hello friends. The question is: is it possible to block deceiver of the trade the usual complaints? My friend foolishly gave items in the hope that this will give him the money. Time I'm here they did not give him. If not difficult, can help you block a pretzel and nacherkat - rep.
Here is the link to it: https://steamcommunity.com/profiles/76561198860621193
To all who will respond, thank)