The amount of people complaining about this is quite silly... Once you attach a one time password they even tell you that you need to log on to your mog-station and write down the recovery password in case you lose your one time token or your phone app resets for some reason.

You didn't follow their instructions properly and now you're complaining about it. Unfortunately now that you've put yourself in this situation you have no choice but to call Square-Enix. Good luck.