Tranny shifting problems
Mercedes isn't much different than any other tranny out there. There are a few taboo things that can screw up your tranny as well as your wallet. I'd check the fluid level after the car has been driven quite a ways. The car needs to be running when you check the dipstick for proper level. What you describe sounds like a lack of fluid, but can also happen when there is an overfill situation. The other problem is filtration. A dirty filter won't suck fluid up while it's cold nearly as fast as a clean filter will. When's the last time the tranny filter was changed? The last item is the band adjustment on the tranny. It's generally reccommended whenever you change fluid, to adjust the bands as well. Has that been done? I don't think you have a true problem with the tranny, but maybe some overlooked fluid levels or adjustments.