We have been a retailer in the past but stopped selling smeg, too many issues with quality, lots of problems with the thermostats. If you need to replace the cooker buy a Britannia or a Stoves model.
http://www.smegrangecooker.co.uk/
December 2009
Sounds like the thermostat is blown, allowing the element to keep heating until it burned itself out.
We had a engineer out today for another issue to do with the fan oven on our Smeg range cooker not maintaining temperature and he said it has happened on cookers he has attended.
Likely you'll need a new thermostat, a new fan element and possibly a new fan
Expensive, but better get someone qualified to look at it in case there is other damage.