Do you have any more storage heaters in the flat, or is it just the one?
Economy 7 should have a seperate fusebox fitted, wired to a timer that turns the whole box on at the right time..
Each night storage heater, should be wired up to a seperate fuse in the box, one fuse per heater. Check the fuse in the fuse box.
If you have other heaters that are also not working, then it's probably the time clock thats failed, and not switching to economy 7 at the predetermined time
The spur it's connected to should only be 'live' for about 7 hours per night. You could try wiring up a table lamp to the spur, to see if that turns on at all during the 24 hour period.
***Be very careful when playing about with these sockets/spurs. The economy 7 time switch can throw on at any time (not necessarily at night)
and a dead socket one minute, can be VERY much alive the next****
You ask my Dad
Hope this is of some use to you. I am only DIY, not a qualified sparks, but I'm confident that the information is accurate...
good luck.
flashbang