It sounds more like linkage issues than transmission issues specifically. It sounds like depending on your mileage you might also consider changing up your differential and transfer case fluids, and see how they look as well.
These issues are getting more common.
Scenario 1.
problems when braking or stopping at intersections, when pulling away the car would rev highly as if in neutral ,moving the gearshift away from drive and back in would drive ok.
Replace the lever ,bush and a spring washer that goes between the lever and the bush, very easy job. I marked the position of the original lever on the rod with nail varnish and also measured it from end of rod as backup. gearshift now glides into positions freely without dropping out of gear, and you can feel the difference.part numbers for some of the parts are
Scenario 2.
A few days ago I noticed that I couldn't get command shift to work but it seemed ok when I restarted the car. Today SWMBO got stuck in a car park only able to select PRN no D no command shift. She rang me for advice and didn't seem too pleased when I suggested she reverse the six miles home with our six month old screaming in the back! While I was looking for LR assist's number she clarted on for a while and managed to get into Drive. I tried it out when she got home and sure enough you can only get into Drive if you whack the selector fully back and even then a slight nudge will knock it out of gear. Is this something I can easily fix (like a loose easily accessible switch) or would LR assist come out as I don't really want to drive it to the dealers in case it jumps out of gear on the A1 and I can't get it back in gear.
You may be able to at least loosen things up, while you wait for the parts, with some WD40, etc. Probably make taking it apart easier as well.
LR012704 LEVER 5.11
TZT500040 BUSH 6.36
WYH000040 NUT 0.75
Bolt (haven't found p/n yet
Spring Washer (haven't found p/n yet
give bush fitting a good coating in never seize compound.
Some HOW to pictures..
DISCO3.CO.UK - View topic - Autobox Gear Lever pivot - How To
when you call and get the other part numbers, etc. post them up.