Just done it, there is a grey compartment at back of unit with a metal spring clip, pull this down then you can get to light. If this fails you have to take out whole unit there are two star screws ( use wide flat head) one on top of light other at side. One on side will also release grill, take of black cover where bonnet release is 4 pop-out plugs. There are another two star screws (need star-bit for this). Last star screw is on bottom of light undo slightly unit will slide towards you, Once released unit is relased indicatior light turn clockwise remove, also another unit push down with small flat and unclip. Then remove grey unit as per above. Done. Then put back together. Takes about 30 mins.
Jon, February 2006