I agree with the above post - I recently changed my bulb for a 'Crystal White' standard bulb - I've had problems with LED one's in the past that don't light the fluctuating current when you set the light to come on when the door opens!
You need to pry the whole of the plastic unit from the roof by gently pulling on it from the windscreen side. Once you have this apart, you will see that the light module itself will separate.
On the back of the module you will see some black plastic tabs that you simply push so they un-clip and the clear plastic will separate from the module giving you access to the bulb.
Only one thing to keep an eye out for is the plastic switch that may pop out if you are a little rough with it, but this is easy to put back into place.
To re-assemble, simply reverse the above instructions.
I actually spent age's looking for some instructions prior to having a go, and couldn't find any. After I completed the job I had the great idea that I should write up what I did, but sadly forgot to take any pictures :-(
I hope this helps - don't make the mistake of trying to pull out the clear plastic using a sharp tool and damaging your plastics!
