Screeching on Acceleration - Help

It's very VERY VERY VERY annoying. So much that I keep the windows rolled up all the time. The car screeches in high pitch ness but not terribly loud when accelerating from stop and low speeds. No screeching at 20ish MPH+. Stop and go City driving, this is annoying and embarassing. Can anyone help me out? I don't trust MB of SF (where we bought car). They are dishonest when it comes to service and will bullshit me with any answer they can pull out of the air.