SE have posted how, but it still involves deleting your character I think. It says they'll issue you a new registration code so you can attempt to merge your service accounts again. This is regarding the situation where you registered your bonus codes to your beta account, and then registered your game to a brand new account, completely wasting the original codes.
Quote:
If, while attempting to transfer character data from your FINAL FANTASY XIV Open Beta Service Account, you mistakenly chose to create a new service account, and subsequently lost the items and character data associated with your FINAL FANTASY XIV Open Beta Service Account, we can provide a replacement registration code to allow you to try the transfer process again.
Please follow the steps below if you wish to apply for a replacement registration code.
·Click the URL below to open an application for FINAL FANTASY XIV Open Beta Service Account recovery.
Click
here for the account recovery form.
·Login to your SQUARE ENIX account if you are not already logged in.
·Read the agreement on the form, and agree to its terms.
·SQUARE ENIX will review the inquiry and the registration code. If all conditions are met, we will send a new registration code to the email address registered to your SQUARE ENIX account.
·Enter the provided registration code, and choose to transfer your FINAL FANTASY XIV Open Beta Service Account.
The application form you go to basically says you delete your character, wait a couple days, and then they'll send you a new registration code so you can sign up again (and do it right this time).
Probably not worth the hassle.
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PS3 Friend list name: Pantherxx Wii code 1629-0463-4657-0263 (revised 9/28/07) Steam ID - Pantherxx010 62BLU 75PLD Reactived 7/5/10 
