They broke my car

I took my car in for a sound system. After a few days the radio just stopped working. When I took it back they said it's the cheap speakers they put in and I must pay an extra R500 for other speakers. As if Prima Facie does not exist. This already made me angry and this owner swear to God that I did not request a specific way of installing my alarm. They did some test pointing on my car as well as I took it for the radio and alarm system the same day. Now there is problems with my electrical on my car and again it's not them, now suddenly they say someone tried to steal my car and shorted wires. What a bull of crap, there is always and not sometimes somebody at our vehicle. We carry a lot of equipment in the car and can not let it stand alone although it is always parked inside customers yard behind locked gates in estates. I wonder today how they are going to explain the stripped wires found on my car....., They provide false reports for insurance claims.