Unfinished/ inadequate repairs and service

I took my car to Autohaus Centurion on 5 October 2017 for repairs primarily for an airbag light which was always on and also some dashboard lights that go on and off. The dealership diagnosed the problem and charged me R2360.20 for repairs. I paid and collected the car in the afternoon around 16:45. The following day 6 October 2017 in the morning, the airbag light was back on. I called the service advisor Adel Beeslaar and she advised that I must bring the car in. The car was taken in on 12 October 2017 as a come back. they called to say they have misplaced the car keys but ultimately found it. The following day on 13 October 2013 the service advisor after discussing with the service manager informs me of a new diagnosis and wants to charge me an extra R1000 to fix what they apparently had fixed a week before, they wanted me to pay twice for the same service. I declined to pay and contacted the service manager Stefan Erasmus and requested him to provide me with customer complaints customer details. rather than provide me with the details he promised to look into the matter and give me feedback. it has been more than a month to date and he has not contacted me and my airbag light is still on.