Old EA Account Unlink

I have a very old playstation account that my father connected hos EA account to about pobably 12-15 years ago and we cant remeber the password to login. The problem is that the email he has connected to it has been discontinued so we cant reset the password either. And when i try to get help from EA they say they cant help me even tho i gave them every information possible of an account that hasnt been used for 10+ years. I gave them the correct email, correct informatiom that no games has been purchased on that account, i gave them the correct olaystatiom id its connected to and still they said the information wasnt good enough. How am i suppose to unlink them so i can connect my own EA account to my playstation.