Honestly if that was the response I received from him, I would first give him a nice #$%^&*( and ask him to go back to training for what he should do and what he shouldn't. If an installer itself has no idea what is the further steps he needs to do, then there is a need that he need to get a job that he knows.

No offense but I think you should really tell them straight on this and ask them stop passing this through each of the department as this will get the problem nowhere but at the end of the day, you will continue suffering. Especially if you are paying money on this monthly on time.