My complaint has been ignored

On the 30 March 2019 my vehicle went for a service to Bidvest McCarthy Nissan Germiston. I was told it needed brakes and new Linings. The service was terrible that day and they were also short of staff. I was shocked as I haven't even had the car for a year and I requested the 20 point vehicle check. All I did on that day was to replace the brake pads to be safe on the road. I contacted the sales person "Charles" to log a query with him, and still no response . On the 4 April 2019 I received a call for a customer satisfaction rating and then I lodged the complaint and received an sms stating that 'Nissan Germiston would be in contacted with me'. Up until now I have never received a call to sort this problem out. I need an urgent investigation as to why they ignored my complaint and all my prior problems that I had and the sales people gave me stories when I received the car. I need this resolved asap please.