Soo i used to have Vip rank in factions, now i joined and i dont... I dont know if this helps, but my account got stolen and they changed name of the acc(have to wait 30 days in order to change name again) if vips are related to username that will be the reason to why i lost my vip, if anyone know a awnswer tell me please
Your rank is on the username you bought it for, changing your name will have you lose your rank and also your gc account.
Have you tried using a cracked launcher under your old username? If not, give it a shot, this will let you log into your old account if you are unable to change your premium name for 30 days. Then when the 30 days are up, you can stop using the cracked launcher and switch back to the premium launcher.