I know this is an old post but I am having the same issue.  I stopped using AT&T almost 2 years ago.  Although my sbcglobal.net email still works, I never use it.  I want my yahoo email and id back, as I had it before AT&T and I use it everywhere.  I keep seeing the, you will get a prompt to unmerge when you disconnect the service or after 100 days it will be unmerged for you.  We that hasn't happened.  Any ideas anyone?