When wiring a house for 'cable', builders are notorious for using the absolute, cheapest coax that they can lay their hands on. In some cases, this cable is so poorly shielded that there is no way to prevent front-end overload, short of replacement of the offending cable.
I would suggest that under no circumstance do you touch any of your neighbor's TV equipment. If you do, you may find yourself being hounded for anything that goes wrong in the future. Even your paying for a technician may create a future liability. Make suggestions but maintain your distance.