Mercedes Benz sucks & they are very disrespectfu

It is roughly 21 months that I have been experiencing this specific noise problem which Mercedes Benz is unable to fix. What is hurting me the most is how the dealership (Sandown Motors & the head office are treating me). My car has been to Sandown Motors 20+ times with no success. In December I logged a complaint with the Mercedes Head Office. I was given this reference number ***. They did not give me any feedback till I had to call them again in early January. I was then told that the recommendation is to take the car to another dealership and I refused as my car has been taken to another Dealership (Zandfontein) and they did not help to have the issue resolved. I called them again 4 times or so and was told that the Head of Service / Customer Management,Lance Moodley will call me. It is almost a month I am waiting for Lance to call me. This experience has brought me a lot of trauma as I am embarrassed to drive the car, taking into consideration I bought it brand new. The excuse given is that it is intermittent, therefore they are unable to locate the root cause. I refuse to accept this excuse. Can someone help me so I my family and I can enjoy driving the car?