Tecnik Built Under Larder Compact Fridge

I've had this fridge for four years and about 18 months ago the light stopped working. I've found it impossible to change the bulb. I can't take the cover off the light. The man who fitted the kitchen can't change the bulb either. Also, the temperature wheel just inside the door mysteriously turns the temperature colder, seemingly on its own. Clearly it is being moved when we are opening the door or taking things in and out of the fridge, but it really is annoying because unless you keep an eye on it, your food will freeze and salads, etc, are ruined.