Actually Fox there is a really really really really and I do mean really small possibility he may be right.
There was a small unnoticeable period were Mercedes automatics and really chuffed up mechatronic units fitted. Added with confusing EGS software and it did lead to some odd characteristics.
type cls and gearbox into google, dont even press enter. the second suggested answer is mercedes cls gearbox problems and then look at all the forum entries, both us and uk ones.