Comcast failure to port land line # to Xfinity mobile phone

Mobile team customer service keeps saying port of Comcast landline phone # to Xfinity mobile phone is scheduled for completion by a specific date, but port fails. Then call again and am assured port will be successful by a new date, but it fails again with no explanation provided for the failure. Is there anyone to contact at Comcast/Xfinity who can actually help or should I submit am FCC complaint?