Looking to set up a line replacement.

Hello! In recent weeks I've had two technicians come over to try and troubleshoot my internet issue, and according to the second technician, the line to the tap that Cox replaced a few years back was not installed underground, but rather out of the back wall and above ground, going under the fence in the backyard. This has led to extreme interference and constant drops in my connection due to wear and tear by the weather, and he said with the permission of my landlord, I can have internal rewiring and line installment done for the house.

I have two questions. One, since this was an error on Cox's behalf, is this line replacement going to cost me extra? And second, is there a number that my landlord can call to discuss the details of said rewiring? Thanks in advance!