Unlinked Steam from unknown account

I have a similar problem, I can't disconnect my steam account from someone else's EA account. I contacted customer support, waited in line for two hours, and they asked me to provide someone else's account details to restore access, although I can't know them because it's not my account!

P.S. about chat, they banned some countries from using support live chat, you can open it with a VPN

They just don't care, the worst customer service