Unhappy client and disappointed.

i dropped my car at the dealer to rectify fault code 029921, Mr Nigel was my adviser, i dropped the car from Wednesday the 8th and when i collected it the 13th January, the car still did not have power, He still charged me R5800 for diagnostic which i was initially told that diagnostic is R3000. The report shows the fault code but he said he was unsure , they will need to assess the car more and i will be charged for that, he mentioned lots of thing which i thought it was just a tactic to through me out and obviously rise the cost. I collected my car and took it to someone who fixed the with less than what i have already paid. I was so disappointed that mercedes benz could not fix their own vehicle and still got charged.