Unfortunately, the hob was defective. One of the switches was faulty. Thankfully, this was picked up by the installation engineer and reported. Smeg are in the process of rectifying the problem. Sadly, it's now a week since the initial installation and we have to switch the burner where the duff switch is, with one of the other switches!. The other four burners work perfectly and very efficiently. But for the problem this is a cracking piece of kit, well worth the money.