Change email assigned by comcast?

I just got xfinity internet. I had never had a comcast.net email address. A year or so ago I had to help my neighbor fix something with their xfinity internet.(long before I got internet from xfinity)  the rep at that time had to create a comcast.net email for me to be able to do what ever it was I had to do. They just plucked the name from my log in email for my xfinity account.  So now I am stuck with this crazy email with my bellsouth email as my email address for comcast.  For example my comcast email says "blahblahblah_bellsouth@comcast.net"  I would like to get rid of the _bellsouth portion of the comcast email so I don't have a rediculous long email. 

Thanks