The problem is simply due to a dud bulb behind the display.  If you look at the clock closely I reckon the display is still there - you just can't see it!  To get at the thing, the entire dashboard top comes off.  If I remember correctly you prise off the speaker covers at the corner to reveal screws underneath - the dash top then lifts upwards to reveal the back of the display and the bulbs come out with their holders.  Renault will rob you for the bulb - you could try a motor factor but they aint so common.  Hope this helps!
                 John
                
 February 2008