Appalling service from Mercedes Constantia Kloof

Took my car in to Mercedes Constantia Kloof for it's A3 service on Wednesday the 25th March 2020 at 7:30am. I also informed the service adviser that the eco stop / start mode on the vehicle was not working. I got a call at 3pm later that day from the service adviser to tell me that a technician was attending to my car. I don't know why Mercedes insist on us dropping off the vehicle between 7am and 8am, if they are only going to get to servicing it at 3pm! Nevertheless at 4:20pm, I get another call from the service adviser advising that - despite them charging the battery for the eco stop /start, the feature was still not working. She advised that I could leave the vehicle overnight with them in order to charge to battery fully so that the feature would work properly, since the battery was low. Got a call on Thursday morning at 8:50am informing me that the vehicle was all sorted and ready for collection. I fetch the vehicle and on the way back home find out that the eco stop / start is STILL not functioning! I go back to the dealer, and the service manager, Dirk, takes the vehicle for a drive to confirm the problem still exists. Then begins the litany of excuses. Dirk advises that the battery could not be replaced despite the car being under warranty, and that they now need to book the car in again to check where the fault was. I pointed out to him, that that was the reason why the vehicle was left overnight with them was so that they can resolve the issue. This fell on deaf ears, and I got an earful of technical jargon. I drive a premium vehicle to avoid issues like this! I now have to take the vehicle back after the lock down period has ended to have them re-look at the problem again. This is extremely poor and inefficient service.