trouble porting number from Verizon landline

I already placed an order to port my mother's Verizon landline phone number to Xfinity Voice. One week after it was promised, the Verizon landline still works (connected to the wall) and the phone connected to the Xfinity modem voice port still has no dialtone.  We are now on our 6th support call. What is the best way we can escalate this to the proper people to resolve the issue?

More background - The regular Xfinity support number for my mother's development (a large development of about 8000 people in Maryland) tells us the port is complete from their perspective.  My mother already completed the IVR voice authorization.  One support person managed to get an Advanced resolution team to call us, and that person confirmed the phone number is NOT ported and that the regular support people were wrong. This person said someone from the "port" team would call us back within 72 hours.  It's now been more than 4 days with no call back. 

I called the regular support number again today and they start all over again.  No way to directly transfer us back to advanced solutions team and they have never heard of the "port" team.  I was promised a callback from a supervisor and that never came either.  We are very frustrated.