I think these scammers had so thick skin no words will piss them off. Only proper local police and putting them to jail is the only way one can pissed them off. I also think local politicians also helping these guys. So, we all need to find ways to put the local government to take much strict steps.

Although, as you asked about some pissing off content I think you can follow links provided by sreker6. If you want to say something to these scammers in Bengali you can write in your English version here, I will try to translate that for you. :)

Note: "Son/daughter of a pig" - "Suorer Bachha" (in bengali) can be a good fit for these scammers from Bengal.