Nck..

NoT sure if you reside in the USA?

If you are in the USA, check the error codes through OBDII port, and check it through the port under the hood. Check the transmission adaptation levels, get all the error codes.

For kicks, look under the car for the drive-shaft issues, but I do not think you will not see anything abnormal. Check both flex disks...

You may have multiple issues:

My guess, The transmission lost the oil pressure regulating solenoid(or o-ring with it. The screen is plugged up). The transmission lost it's core fluid flow into the galleries. Overheated the bearing/bushing in the torque converter turbine, and possibly damaged the weak K2 bearing which will damage your planetary gears. The banging is coming from the torque converter impeller floating around. The whine from the planetary or oil pump gears.

One more thing, you could have a transmission oil filter collapse or damage
Make sure your fluid and filter is current!! Up to level.

Get your self a Mercedes 722.6 transmission dip stick measuring tool for a piece-of-mind.

hope this helps,

Martin