Mercedes Inferior Quality and customer service

I drive a 2016 Mercedes A45 AMG, which is still under maintenance plan and warranty. Was on my way to holiday with the family, about 60kms out of Jhb on the N12, my panoramic sunroof exploded and flew off. Was extremely traumatizing especially for the kids. Sounded like a gunshot. The response I received from Mercedes SA via the dealership Constantia Kloof, was that glass is not covered and I should not waste their time. I am extremely appalled with the response received. After going online and doing some research, I have found that this is not an isolated incident. This is a defect on the car which is even more appalling. To purchase a car which cost approx R800 000, one has greater expectations than this. This will be the first and last time that I or any family member would purchase a Mercedes.