Bad Service

I took my car in at Eagle Canyon Auto on 01/02/2016 for a ABS warning light and a engine management light, I was told that I their diagnostic laptop is faulty and they will call me when it is fixed. So I asked if they cant refer me to another GM dealership to go run the diagnostics on my car and they said I must wait. I called in after 3 weeks since I didn't get any feedback from the service department and my car was booked in on 08/03/2016. they ran diagnostics on my car and I was told that they could not pick up any faults on the car but they picked up a high voltage alert which means I have to change the battery on my car as that is what the issues is, why didn't they test with another battery? I argued this with them but I ended up buying a battery which costs R2k. only to find that the battery did not fix the issue. They booked my car in again on 11/03/2016, they took my car to another dealership to run diagnostics and picked up a whole lot of sensors that need to be replaced, they confirmed that they will replace the parts in warranty and they will book my car in on 17/03/2016, I called in confirming my booking and I was promised a call in 2 minutes... till now!!!!