Storage Heater coming on during the day - Why??

Bexm

Hello!

We've been living in our new house for about 4 months now and we have one small storage heater, we are on E7 electric, and our hot water also heats up at night by a timer.

We were never left any instructions for the heater, but our new neighbour came round and showed us how to set it.
We were under the impression it heated at night and just released the heat during the day, but it seems to be heating up during the day (not all day, but definitly does come on for a bit).

We have had it turned off at the wall until recently as its not been cold enough and it doesn't appear to have an on off switch otherwise.

How does it know what time it is and when to come one? Is there a clock somewhere I need to set, that must have been reset by turning it off?
If its coming on during the day surely somethings wrong, but I'm not sure what to do about it and it'll cost me a fortune??

Any advice would be much appreciated!

Thanks

Becky