Whining is a vague description. What drivability issues are you having with the transmission? Of course the car is mechanical, are you sure it's coming from the transmission? I can think of a lot of other items that can making a whining noise. It might even be normal if this is the first time you've driven it. MB transmissions are known to be sluggish, I would do the ECU reset for the transmission so it relearns the shift points.
Are you sure it's not the motor mounts/transmission mounts? Those make everything louder when they're shot.netural or park when i press the gas the noise increase with the rpms i even took off the belt and started it and getting the same whining pitch noise so its not the powersteering pump or wheel bearings