Well, I hope all these work as mentioned by OP, because despite you trying to set a filter and add block advertisers, verified users, and the like, they can still be annoying,
very annoying set of people. Why put out a rate you know you can't trade with? They tell yu its for competition and all. I'm so tired of the way Nigerians do things tbh.
After all, you can't escape these scammers by any chance, but I think the exchange is now fully aware of these abnormal behaviors and is taking action on accounts found in such menace.
The exchange is not doing anything about it. They should make it in a way that traders cant negotiate. The rate you put out is the rate you pay. Instead, they encourage the negotiations and fee rate of the traders.