Apologies if this has been posted before, didn't find it on my initial search, just mostly posts asking people to remove them outright, or just other random stuff. O.o (is search not working properly?)

Anyhow, my suggestion is thus:

Square Enix, let us, the community, help you!
Give us the option to do a Right-Click report on Gil Spammers. Have the system place the person on a list that appears directly to those in charge of cleaning up these people/bots, with a snapshot of the message we're reporting them from, so that it's easier to find them.

Many other MMO's have this system in place already. It doesn't automatically ban them, or mute them, on the off chance of some people using it to troll or abuse. But it does let us help you out, and keeps these kinds of reports separate from all the other reports/bugs/in-game messages from players.
(Since the current system forces us to post these to the same place as a report for a bug or malfunction)

I'm already right-clicking to add them to blacklist, so it would not take me that long to do it again to report them to help you out.