Xfinity Dropped our 2 phone lines

Xfinity dropped our 2 phone lines without permission late November.  We have talked to over 6 techs in the last 30 days and nobody seems to be able to fix our 2 telephone numbers that were dropped.  We are told that it will take 48 hours and nothing is done.  We have had these phone number for over 40 years and do not want to lose them.  We need to get these phone lines operating again.  Please help.