Connectivity issues since receiving new modem

Since receiving a new modem a few weeks ago I have experienced numerous connectivity issues and after probably 15-20+ phone calls to Xfinity I'm close to cancelling my account after having many years of good service.   Because of COVID my husband uses the internet function for his work which has made the disconnect extremely troublesome.  This all began when we changed some of our service and, without our knowledge,  the agent disconnected our fax telephone line (which we use for business).   PLEASE PLEASE PLEASE CONTACT ME OR SEND A TECHNICIAN TO MY HOME TO GET THIS REMEDIED.  I can't continue to call and get those xfinity recordings............and, talking to someone in the Phillipines has not remedied anything.