Hello @vvhathegg,
when you relink your account, there's always the chance that the progress cannot be restored - relinking your account to the original account is the only way to get your progress back, but there's no guarantee. The fact that it messes with your account is also highlighted in the original unlinking warning that you get when you unlink and also in this article:
https://help.ea.com/en/help/account/unlink-gaming-accounts-from-ea-account/
Unfortunately, if Support checked your account and told you that it's been overwritten, then there's nothing that can be done.
Bitte schickt mir keine Direktnachrichten für Support - taggt mich im Forum @EA_Pythia