no concesus of what the issue is from 4 Xfinity tech visits. Help

My 8 unit condo building in Lincoln Park, IL, has had connectivity issues for 6 weeks.  The first tech diagnosed an issue with the Xfinity line that runs from our mechanical room to the pole in the alley behind the building.  He requested the maintenance/construction group to come out to check that line.  No one showed.  I reached out again, via numerous "chats" etc and Xfinity sent another general tech, but not one that could look at the line outside.  Again, I spent so many hours trying to speak to someone to explain the issues and xfinity then sent another general tech.  Again, not the maintenance group.  Finally, they referred me to their outsourced "cable installer, etc. company" who wanted to run the coaxial cable inside conduit all around my building and up the outside of each unit.  I did not think that was going to solve anything but alter the aesthetics of the building.  What I need is for Xfinity to send out their maintenance people to check the outside line into our building to determine if it is damaged and fix it if it is.  If that line is not damaged, I need the maintenance group to determine if their is an interruption somewhere in the lines that go from the main connection to each unit.  The HOA needs an affirmative answer as to what is wrong with the connection and where that problem originates.  We have had 4 different techs give us 4 different reasons and that is not acceptable.  Please let me know how to get someone in xfinity to come out to try to diagnose the problem.