We also had same problem, but it's actually very easy once you know how. You first need to lift the glass front off. Then undo 2 screws on each side towards the bottom of the fire that hold the bottom front plate on. You may need to loosen a screw on each side that holds the base that the the pebbles sit on as well (but don't take out). Then just gently prise the bottom front plate off. You then have access to the bulbs and replace as you would a standard light bulb.
Simon Ingram, February 2011
