FC 24 can't log in to EA Account

Okay, I think the problem is - somehow - my Xbox account/whatever it is that has been linked to my EA account has got linked to a 'disabled' one (it is in the URL but the email address is hidden) or just to the wrong one somehow. Since I have now bought FC 24 for my son and he wants to use online features, I need to get this resolved either by swapping to the EA Account I am using here or by just somehow someone removing all ties to the 'disabled' one so I can assign this EA Account to it myself.