Renault Benoni

I'm not happy with the service that I have received at Renault in Benoni. I took my car to Service on Wednesday which was never a problem, before I took my car I had an invoice that my service for the car will cost R9,5k something which I understood. To my surprise i received a call from my dad because I took the car with him since I was at work. My dad calls to inform me that they have discovered new problems on the car which i understood. My problem with the Renault is that the car for for service was R9.5k something and the discovered problems was costing R5800 and the agreement was for Renault to fix the discovered problem only and leave the service because the budget that I had was R9.5k for the full service. Today they called for the car to be fetched now the car to be released it requires R9700 the amount that we never agreed on. They telling me that they replaced some things we never spoke about. Everything that was replaced was never given to us to see if they have replaced them. I loved Renault wholeheartedly but I'm not servicing my car to Renault anymore. I'm ****ed I'm very angry. We all work hard for our money, if that is how their service runs then I'm out. I would never recommend it to anyone. I'm disappointed. How do I even trust them with those things that they said they have replaced if we can't see them. They keep changing the amounts to their clients every 2 minutes