I have doubts that the tiptronic system on my c200 mercedes works properly.when i shift ,the engine takes about a second or two to respond ...is that normal?And there is a kind of minimal jerking when it responds to the shift.
sounds as though the gearbox is low on transmission fluid,
drain the fluid change the filter and top it back up with fresgh fluid and see how it is then. if it is still the same i know there is a sensor on these gearboxes which sometimes fails. (seen this sensor fail on ml270 jeep and resulted in lack of power jerky gear change etc. hope this helps.