It depends on the dealer. Around here MB of Fairfield are SOB's, and would charge you $125 an hour to change it. While pissing and moaning that its an old car. MB of North Haven would probably do it for cost.
MB of New London from what I have heard will not only do it for cost, they will detail your car as well and give you free coffee.
From what I have been told...their customers are LOYAL.