Need to change yahoo.com email password.?

I am in account hell now. I have a yahoo.com email address that has been compromised and Yahoo says that is has been merged into ATT-Uverse and when I try to go through the Yahoo process to change my password I get redirected to ATT. But the ATT account process doesn't recognize my Yahoo email address. I have tried calling in both ATT and Yahoo and they keep pointing to the other guys. Help! Is there a phone number that I can call that supports the Yahoo-ATT accounts and can track my so-called merged email and help me change my password?