email support for an old ameritech.net email

Help! I have been trying to get help with my ameritech.net email. It is not a U-verse email. It was set up years and years ago. I have tried to call in, but since I don't have an account number or telephone number the representatives tell me to call Yahoo. I called Yahoo and the told me ATT owns this email and I should call them and ask for the email support team. They gave me 5 different telephone numbers to call and after 3 hours I gave up.  My problem is that this email is also showing two other emails when I log in. Somehow the are linked to this email and I cannot figure out how to turn them off so that my coworker cannot read emails intended only form be by logging on to this email.