Indeed you have reached the improper outlet for assistance on this matter. But you do have it right in that a Game Master will be the one to take a look into this issue for you. You will first want to ensure that the Destrier Beret code was attached to your Square Enix ID and that you selected the right PlayOnline ID in that account. You should be able to talk to the Festive Moogle in town and grab the item if everything worked correctly but failing that you'll simply need to go through the petition queue for them to look further into your character and account. Just in case you may want to include as much information as possible in your /helpdesk message so that you can be responded to appropriately.