CL1FF

I am looking for advice on reparing or replacing the right paddle shifter which is malfunctioning on my 2006 C55. It still functions but appears to be stuck or broken, so downshifts are either negated, or when I am able to actually downshift whether from the left paddle or the shifter, it only holds that gear momentarily before upshifting right back. This does not affect normal driving in either "S" or "C" transmission modes, but it has rendered "M" completely useless and does nothing for controlling gears going into or accelerating out of turns during more spirited driving efforts.

I'm hoping someone here has some ideas or resources to help me. Can anyone point me in the right direction to fix this? -c