Buying a Mercedes Benz, was the biggest mistake of my life

I bough a Mercedes in 2019 brand new. I took a couple of extra's being the sunroof. 2 years down the line the sunroof stopped working, I had informed them of such and they were refusing to sort it out because they claimed it was out of warranty. Eventually they agreed because they said it will be goodwill. My vehicles has been gone for over a month for repairs and to date its still not back. I requested for a courtesy car from them because, I am unable to go to work but they are refusing to grant me a car. This was a mechanical fault and yet I am expected to take the blame for a mechanical fault. I am really unhappy with their service. They are messing with my livelihood. I may lose my job because I use the vehicle for work and I can't go to work due to this incompetence.