Support unlinked account

My son and I share an Xbox.  We couldn't get the season pass for Fc26 today because the account wouldn't sync for some reason.  Its been fine until today. When I tried to link the account to the platform it said we were already linked to an account registered to [partial email address].  I didn't recognise the email address so the support agent asked me if I want to unlink the account.  He made no mention of the problems this might cause, which I've subsequently found out.  I was then informed it was linked to my child's account after all, they just anonomise the email address which is why I didn't recognise it.  Child accounts can't now be used for linking to this platform and linking it under my parental account, under which the child account sits, didn't work either.  He has saved and spent so much birthday money for this account and now we can't unlink it again until 2027 !  They've taken hundreds from us and now I can't access the game for a year because of bad advice from EA support.  Is there anyway around unlinking the account again.  I think ea should be able to bypass the cooling off period when it's their fault I'm in this position.