HELP - Mercedes E shutting itself off
 

I do not have much expertise in Mercedes cars. I am writing about a problem I had and would appreciate your guidance.

I bought a Mercedes E220 CDI, with automatic gearbox, and I have been driving it since then, although so far I have only made around 25,000 km. In the past I had a problem with this car, where after I start the car and shift the gear into D, the gear would get stuck and would not change up. Hence the car would not accelerate. In such cases, after I stopped the car, and put the gear to P and then back to D the problem would go away. In any case, I mentioned this to the garage when I took the car for service, and they said "there was a leak" and they fixed it. For a while, I did not have this problem.

Recently I was driving (at around 40 km/h) on a deserted road on a rainy day and it seemed that I had the same problem. I thought, rather than stopping the car, if I shifted the gear from D to N, and then back to D, the problem would be solved. Instead, as soon I pushed the gear the car started chocking and it stopped, and the engine shut itself off.

After this incident, the car started normally and I continued to drive without a problem.

Since then a number of questions are haunting me:

Is it normal that the car would shut itself off if the gear is shifted to N from D while driving?

Is this a sign of a bigger problem? (You can imagine what trouble this can cause in traffic.)

Have I damaged the car by trying to shift the gear to N while driving?

What can I do to ensure that this problem is not repeated, so that no harm is done to myself and my family?

I will go to a Mercedes garage but I am concerned that I may not find someone who would patiently listen to a novice like myself. So any thoughts would be appreciated.

Thanks!

Sorry, I forgot to mention that I bought the car in 2006. So it is not even four years old.