For some people a few hundred dollars are equal to ,,multi thousands'' and I think its worth to contact your country's official bodies. As I get the information(which may not 100% true) there are no official bodies to complain against crypto scams but you may try to contact police. Another solution may be to contact the exchange and report the feud actions against you.
The amount someone is scam with matters, if it is just small amount of money, investigating who the scammer is may not worth it because the victim will pay money for investigation which is in thousand dollars, so if the amount is low, the person should just overlook it for not to lose more money which does not worth it at all. But if the amount is huge, it can be reported, like to his lawyer that know the next appropriate step to take.
I've just heard that citizen pays for the investigation, its a little bit strange for me I mean if someone doesn't start private investigation.