CHARGING ME MONEY FOR THE REPAIRS YET ITS THE TECHNICIAN WHO RUINED MY CAR!!

Last month I signed up for camera and tracking device. The tracking device and camera were installed separately, after the installation of the camera the car aircon did not work. I called Cartrack and informed them of this and asked them to come and fix it as the problem was caused by their technician. They sent someone to come and check the car. The technician with the code CT5(9)71044 confirmed that the issue was caused by the fuse the technician who installed the camera mixed up the wires(fuse) and explained thats why he had redo the some installation. Now week later Cartrack is billing me R600 for repairs as if they repaired the device. I have explained to several consultants this matter without getting anywhere. Based on this treatment I'm considering to cancel my contract because Cartrack wants me to pay for repairs yet the problem was caused by a Cartrack representative!!