Well if you are unsatisfied with that dealer, you can do a few things.
1. Go find another dealer, explain the problems you had with the other dealer, and see if they will treat you and your car better.
2. Call Mercedes benz USA and complain to the rep for your area about that dealership and what they have done or not done.
3. talk to the manager of your dealer, and tell them your are unhappy with the service you have been given, point out the mistakes made, and the noises that you hear, and tell him you want the problem taken care of.
You are the customer, and you are entitled to proper service on your brand new benz, if they aren't giving you proper service, you need to take it up with them, or take it up with Mercedes benz USA, who does not appreciate it when dealers treat customers poorly.
As for the noise, I think you should find a dealer that you can work with, the car is under warranty. Keep taking it back for the problem, until you have reached lemon law limit, and then demand a new car.
I had a friend who did that with his S600 a few years back, because of a steering shudder at 60 mph. He kept taking it back for the same problem within days of getting the car back, after the 6th time, he drove in, and invoked lemon law and left an hour later with a brand spanking new one.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.