If you’re unaware, RMT’s, or real money transfers, are basically illegal in virtually any such game due largely to the fact they can bring severe imbalance to the game. They’re also called out in various Terms of Services for several games.
Square Enix issued over 5000 such bans during the period between February 25 through March 3 for participating in RMT or other prohibited activities. There were also 814 accounts banned which took part in RMT advertising.
If you come across anything that looks like an RMT cheat, be sure to report this using the in-game commands: [System Menu] -> [Support Desk] -> [Contact Us] -> [Report Cheating]. Additionally, you can right click the character name in chat and select [Report] -> [Report RMT Activity].
Due note that these reports will be process automatically, at which point, Square Enix will determine if these break the Terms of Service by falling under the RMT banner. Just don’t cheat, people.