Hi Ricardo,
the proper way to do it is to first remove the ash tray, then the four screws to allow the 'T' shaped front fascia to be removed, then undo the for screws that hold the heater control box in position and wiggle it around so you can get to the back of it to access the bulbs { there are only two of them } they are quite hard to see and get too.
Alternatively, you can actually just peel off the front of the fascia and take the bulbs out that way.