Sadly there will always be ppl that buy gil. Ofcourse they deny it. But as long as there is a market there is a sale. Its like drugs in the RL.

But do your best to report them, I would also recommend ppl write down chr name of the gil seller spammer, report him/her. Then wait a few days, do a search to c if player is banned or still shouting for gils on sale. Curious if they actually ban ppl now or not..