Ridiculous pricing and bad attitude

I took my car for service to MI Service Centre in White River on the 14th of March 2016 . The issues that were supposed to be fixed were as follows: Clutch Kit, Idling, 3rd Gear and Oil leaks. I got a call from David who then confirmed to me that they will charge me R4300 to fix the abovementioned issues. I agreed to that. He then called me again and told me that they need to order something else and that the charge will be about R4600 and not more than R5000. I told him that as long as it's not above R5000, I'm fine. Later David called me and he tild me that they could only fix the clutch plate, oil leaks and the gear mounting. They could not fix the rest. The price still was not more than R5000. On the 24th of March 2016, I called David and he told me that the car is fine I can collect it. Upon my arrival they were not done with the car. It could not start and one of the mechanics dismantled the wiring in front of me and apparently as a result, it damaged the alternater. Now they are charging me R5480 for a service not provided. I can't afford to pay that much if my issues with the car were not sorted. Please let's help SA, companies like MI Service Centre are ripping clients off