Unidare storage heater not working?

I have 2 storage heaters both unidare and neither work. the controls don't seem to do anything and the technical support line don't want to know about it. I am thinking it is an element or thermostat maybe both, can anyone shed any light on the situation please. The models are, wmx712n, serial no.00024936. And wmx724n, serial no. 0001618.
Many thanks, Stuart.