how can i fix my delonghi gdf 603?

i have a cooker that has a gas hob and electric fan assisted oven everything works [gas/defrost/grill] but the only thing that doesn`t work is the oven it comes on that is the fan but it doesn`t heat up people have suggested the thermostat/heating element/a fuse but the digital clock works fine any sugestions cant keep using the combination micrwave to cook the roast.fran