Poor workmanship and Customer service

I took my Mercedes C200 for a service to them. When collecting the car the car was jerking under acceleration. I immediately turned around and went back. After the poor technician tried to find the fault, I am not sure he knew what he was doing with the diagnostic tablet I ask to speak to the manager. About 10 min later a person walked in not even introducing himself and told me that the items on the invoice is guaranteed and if I have an issue I can go and see a lawyer or the Ombudsman. Dealing with such an *********** and no customer skill person was frustrating as I was an aftersales manager for 16 years for a luxury brand and never treated my customers like that. I made a booking with Mercedes in Nelspruit and within 15 minutes after they took the car in I was informed that the spark plugs ACD fitted was incorrect. I had them replace the plugs and took the invoice to the dealer principal of Malelane Toyota as ACD is part of them. He made a lot of good promises and he will sort it out but 3 months down the line and 2 follow ups with him I still have not received any refund from them. I will not recommend any person to ACD or Malelane Toyota as their customer service is shocking!!