SE just need to re-inforce their rules and be more strict. Start Banning the person who buy gils as well. So far they only Banning RMT once in awhile, it is not enough. Player who bought gils think they are getting away with it and no consequence for buying Gils.

Every time they do a Maintain, create a global message that say "We are beginning maintain shortly. We are looking through our Database and Banning Gil Buyer as well as RMT. If you cannot log back in, it mean you are Banned. Please look forward to it."