No way to remove Apple ID -> Game Link?

I'm an Android and PC player, and after time away from the game have come back to find my account taken by someone else. 

I changed EA Account and Google account passwords but found that someone was still accessing the game and I was getting frequent session changes (not to mention my in-game name was changed, I was in a different guild, etc...). Although I've never played on iOS, I tried to link my account to my Apple ID just to secure that entry path to my account. I was unable to do so, as apparently a link already exists to another Apple ID which must be what the intruder is using to access the game.

Over the last seven days both the 'in-game help team' and the 'dedicated help team' (accessible through the EA Help site) have bounced me between them and both state they can't do a thing.

In-game:

'Dedicated' team:

Is this really the case? if that is correct it seems like a major limitation in the ability to provide a secure service? 

Can someone advise if there is another team or way to have this resolved?

If not, I consider the account unusable and guess I can lodge a case for a major failure rectification through my state's consumer affairs (as I have spent $1k's)