RevidnaV,

The information provided by Dragoy is correct. For anything related to the link between a PlayOnline account and an Xbox LIVE GamerTag, you’ll need to contact the SQUARE ENIX Support Center for assistance. After proper verification, any agent would be able to assist you further with your concerns.

The SQUARE ENIX Support Center for North American accounts can be found at this link:
SQUARE ENIX Support Center

The SQUARE ENIX Support Centre for European accounts can be found at this link:
SQUARE ENIX Support Centre

The SQUARE ENIX Support Center for Japanese accounts can be found at this link:
SQUARE ENIX Support Center