Siemens Ceren Not Working?

I have a Siemens Ceran induction hob, which up until now has worked perfectly. It still switches on, the numbers come on and remain constant (with or without a pan) however do not heat up. The system seems to think that they are heating, given that the numbers don't flash and the h appears once switched off again, but they aren't.

What has gone wrong here and can this be fixed?

Many thanks,

Calum

Calum
October 2014