You can report him by ticket. http://support.rpg-club.net/?language=English
Refer to server rules:1.14
Interfere with the other players’ gameplay, mechanically restricting their access to locations or NPCs. (for example, blicking access to the GC with summons, pets, transformations, etc.).
Anyway, it can take some time. I don't know if it's intentionally but I would see the solution in making different nick of trader and trade your items from main in other town.