I mean, now the predators know that she is underage cause you gave everyone her name. Report to ATA in a help ticket. They can only ban if she's disclosed her age in a public channel with proof. So if she said it in pms and gifts they can't do anything.
You can also contact a moderator (like me) if you find proof on someone's wall or even on her own profile. In case I'm not around, press here for the list of other moderators. Locking ?