Unable to access Xfinity email through Apple Mail App

First, Xfinity has never contacted me about the migration of email services to Yahoo.  I have paid 2 different computer guys for 5 hours of work to regain access through Apple Mail App. and it doesn't work.  Last word from them is that I would just have to wait until the migration is completed.   I am concerned that it will never be fixed, and I will be stuck with the unwieldy way I am having to work. Has anyone on the forum been able to regain access through Apple Mail?