EA account not working on ps5

I brought battlefront 2 and went to play so went to link my EA account to my PS account but it says there is already a EA account linked. 

The linked EA account is a (hidden) email address I do not recognise therefore can't reset the password, so I cannot get access to it to unlink my PS account and add my actual EA account. 

It is probably an old EA account or a friend's account from when I was using my PS3 over 10 years ago. 

How can I unlink the old EA account to my PS account? PS live chat was no help, saying it has to be through EA. So I made a case on EA website but no response and doesn't look active, not sure if it is working or not. 

Thanks