Mccarthy VW Constantia: Brought my car in in good condition, after service it couldnt start up and 11 days later its still not fixed. And they want me to pay just to see what the problem is.

After picking up my car drove it for 3 KM and car could not start up. 11 days later after sending and calling forever i still don't know what's happening with my car. they expect me to pay for them to diagnose the car. The service agent doesn't bother to call back, they called me after that and i filed a complain but hey. I have sent lots of emails to services agent and principal dealer with no success. Have been taken my car their for years but it doesn't matter to them. I am so disappointed and lost all the trust and brand reputation with me is at its lowest ever.