Rhod's write up sums up the job.... remove the 2 footwell cables and the underbonnet cable by the air scoop.... simple clip and a pin/loop type hook up....... then 2 radio tools and out comes the control with a quick tug (guiding the cables as you do so......... there are 3 bulbs as Rhod says .
My hot/cold slider bulb was blown....but while the unit was out I replaced all 3 bulbs so I don't have to bother if another one decided to blow now the unit has been moved about......... refitting is reverse of the above process and you can get the cables in the right place.....as the plastic will be marked by the metal clip.... job done
The Bulb you need is a 286... a capless push in job.....
you can get colours but I fitted the defaul clear bulbs....and at 43p each at the Motor factor.. 
.......not Halfrauds as I didn't want to pay £1.89 eac 
h ......... I decided to buy 10 so I have some spares....