Hi, I have a similar problem. Engineer was at my house today and it was a loose wire behind the light in the oven. As the wire was loose it was touching the metal casing of the oven and causing the thermostat to short circuit and bascially the oven was on at 'full heat' every time we turned it on regardless of the temperatere setting on the knob. This resulted in the whole thing burning out. In our case it was a manufacturer fault and therefore Currys will be covering the cost as the product is only 15 Months old. It was an Indesit engineer I got out at £104 which is pricey but I was confident the fault was a manufacturer fault.
Longer Guarantees!!!!, December 2009