I have a 2006 W203 C350 with the 7sp Auto. Ive started to hear a lot of Gearbox / Transmission whine. Its worse when you lift of and goes when you apply power.

Im worried that it could get worse and the car is under warranty so can I have some pointers as to what it could be?

I want to be armed with knowledge incase they dealer does the 'they all do that Sir' line

My M5 used to do it but that had 150K on the clock and the C350 has just passed 64K.