You need the model and the 12 digit service number, which is displayed on a sticker or data plate. For cookers and ovens this is usually behind the oven doors (around the frame). For hobs this is usually on the underside, side or back of the appliance.
Here's What you should See
Your model number may be a combination of letters and numbers and could also include characters such as a dash (-) or a slash (/). The service number will consist of 12 digits starting with the numbers "85".