Smeg oven not heating and no.6 flashing on the analogue clock?

smeg oven if over a year old but only been fitted 5 months. The fan is going but the oven is not heating and the no.6 if flashing constantly on the clock. I have tried unplugging it, various heat settings and various settings including the grill but nothing is happening. I have tried leaving it for 6 hours in case I had accidently put on a delay timer but still nothing. Does anyone have any idea what is wrong with it?