Sounds like they are throwing parts at the problem hoping to cure it. If you are hearing static and hissing on the voice line there is probably a wire problem. If you could get an experienced tech out there with a low tech KS meter or Sidekick meter they could probably see the problem. Its not rocket science, all they have to do is isolate the wire portion of the circuit from the vrad and look at it. Have they looked at the inside wiring with a meter? If not then your inside wiring could have a problem. You need an experienced repairman out there not wantabes.