2007 Mercedes Benz S500 squeaky brakes

Brakes problem
2007 Mercedes Benz S500 Four Wheel Drive Automatic 5000 miles

I actually have a 2007 mercedes s550 4 matic. My brakes have been squeaking alot when I stop. I've brought in my car to the dealer twice and both times they've said that it's normal for high performance cars to have squeaky brakes and there's nothing wrong with the brakes. Is this true?