ZANUSSI product warning: Zanussi ceramic hob cookers have a generic mad temperature control system which means it's almost impossible to cook anything properly that requires consistant high heat. The rings keep turning down. e.g. heat chip pan oil to 195 degrees, put in chips, and the hob turns the heat down to low and stays there for ages, not registering the 60 degree change in temperature. The Zanussi franchise engineer tried to test the hob without a thermometer, saying he couldn't see a fault. I suspect they are instructed not to recognise this obvious fault. Here's the YouTube link:
https://youtu.be/wyAGFIH7PjM