Unidare FS24 storage heater not working?

Hi

I have a Unidare FS24 storage heater in my flat which has suddenly stopped charging over night. I turned it on for the first time this winter last weekend and it charged fine for at least one night but for the last two it has not charged at all and is completely cold this morning.

I have made some obvious checks and established the fuse in my fuse board is ok and the fan still works but am at a loss as to what to try next. Can you give me some advise on any common problems and solutions and I will get someone with some electrical knowledge to take a look and attempt to fix it.