Overcharging for theyre mistake

Overall I am a happy customer, but I am unhappy with their service due to not admitting fault, since they came to instal our fibre they did not put the fibre cable in a concealed pipe and they did not hide it in the ground they left the wire exposed on the ground, my dog accidently bit the wire, now they charge me R1700 to come and put a new wire in, where they should have burried the wire, so it is not our fault entirely, for me I feel they should charge us less cause they left the wire open on the ground exposed to anything.