Having done this job myself on my A6, it's a piece of cake, same as my Merc.
Don't bother with the updated fluids ( which is lifeguard 8, unless you REALLY get all of the old fluid out, the software update is a bodge, as it kind of tells the g/box to slip the tranny / brake bands more / less ).
All the A6s were filled with ZF lifeguard 6, stick to this & ONLY ZF fluid & you will be fine.
Mine was the original fill, yellow lifeguard 6, and it's readily available ( I think I used a well know retailer up north ), I did the pan, sump filter & flushed the torque converter & full refill, then top up at the correct temp.
My box just turned 48k, so the fluid that came out was definitely a bit worn & WELL worth doing. No real sludge, but certainly signs of wear / grey slime on the filter body.
When the weather is better, i'll do the direct shift box & the other bit.
It can be a bit messy & you MUST have the car level, but it's certainly do-able ( oddly enough the BM 5 series use the same box, but they use a throwaway pan assembly which has an intergrated filter ).
I would suggest that there is NO SUCH thing as oil 4 life..... this will certainly require a new AT in the future.
cheers
