Victimazed by the dealership and Mercedes SA

The experience and treatment ive being getting at the dealership its traumatic. I've been a brand new 2019 A class 200 last year in September I've been experiencing mechanical problems with car since 3 months of purchase. The dealership has made the problems to look like minor problems and worse now the car is overheating, they took my car in for repairs for 5th times since I bought the car. I was given a courtesy car and I got involved in an accident now I'm made to pay 75k. As we speak I dont have a car while I'm busy paying for my car and now to top it all I have to carry all the damage of the courtesy car alone. Had they not sold my a car that have endless problems I wouldn't be in this situation currently i find it myself. I have expressed my frustration with this and explain I dont feel comfortable driving such a car and I was told I must just trend it in and again they is a shortfall of more than 100k still they say I must carry it myself as if I brought this problem to myself. I find my self psychological exhausted with this dealership and Mercedes SA as they are not helpful at all I've complained to the principal dealership and Mercedes SA but I didnt get any assistance from them.