Very poor after-sales service

I had New Vision install a 4-channel camera system for me in August 2015, for which I paid them in full (R14,998.00). They installed 3 cameras inside the house and 1 outside. Since that first week of installation, the outside camera has not been working. It shows a fault which I cannot fix - only New Vision can fix. After phoning Rudi and Bennie Lombard several times, and after several occasions of no-show to fix the problem, they finally sent technicians over to replace the camera toward the end of January 2016. After the camera was replaced, it worked...for all of 10 minutes, and then went back into fault mode. Again I have been phoning Rudi and Bennie repeatedly to try and get someone to resolve this problem, as I have NO outside camera functionality - this is supposed to be a SECURITY camera!!! I finally managed to get hold of Bennie on Friday 11 March 2016, who promised me that his guys will come over to fix the problem around 14:00. I kept checking with him that Friday afternoon as it was going past 14:00. They never showed up on Friday!! I have been trying to call Rudi and Bennie since that Friday afternoon but they do not take my calls. How's that for after sales service?