Poor service

I called them to come in and install my open view decoder. As soon as they left, it stopped working showing an error message on the screen. I informed the guys, they first said they had now idea what that was and had never encountered such a message. Later they said the issue was a faulty power cable and that I should pay R800 for them to assist. For a job not well done and the money I paid them, i expected that they come back and resolve the issue at no expense to me.