I can feel your pain and frustrations. I have gone through similar expensive excercise with my previous 190E 2.6. I often wonder if Benz do make good cars, esp. if a Toyota etc can go through life without actuators, this and that valves and all those wonderful relays.
But despite all this, I am still with a Benz so my conclusion is that I am a nut-case or a voyeur of some sort. The pain and suffering (mentally and financially) really does something for me!.
All the best.