Factory stereo controls for steering wheel (XPD500500WVH) - point 4 on my post. It is one of the cheaper parts from LR Australia.
To install, you need to make a tool (out of a coathanger) to pop the steering wheel airbag out. Sounds scary, but if you take your time and disconnect the battery +ve terminal - not a problem. There should be a guide on disco3.co.uk if you search.
Edit: Here are the instructions from someone else that did the job:
Left car parked up for a couple of hours, although if the EPB light has gone out you should be fine.
Then disconneted the battery.
There is a small slot on each side of the steering wheel. This is where you need the airbag removal tool. Basically a small hook. As I said you do need to give it a good tug to release the retaining clips.
The rest is simple just remember to remove the 4 Torx screws before you start. This way you can have the ignition on so you can turn the wheel and get at the screws easier and not struggle like I did.
