Thanks for the feedback, its helpful to the forum as often people just go quiet and we never get to find out the outcome of problems.

My theory on the battery comes from owning an auto Mercedes which does strange things when the battery gets a bit low after short runs during the winter, it causes snatchy upshifts and shift lag which is well documented on the MB forum, if the battery is kept topped up with a trickle charge at weekends its as good as gold.

It sounds like the fluid change and filter clean did the trick in your case, glad you got sorted.