Possessed Heater?!?!?!!!

In addition to what Paul says - it also could be that theres some botch job other wiring which you can't see that's causing the issue. Paul, you know what I mean by that, you might 'think' you're looking at what must be the only point of failure but more digging around results in the real point of failure elsewhere and especially where you weren't expecting it to be had the job been done properly.

For sure.   Based upon the switch on the hardwired connection being (supposedly) off, a bad switch seems the most likely as the unit wasn't getting hot before the switch was turned on, but if somebody has done a hack job on the wiring it could be something else.  Some of the stuff I've seen has to be seen to be believed.

Either way, you've gone about as far as you can, and if you're not familiar with the wiring involved, it's time to call in somebody who is. 

Call the landlord to get the thing disconnected.  Storage heaters are rubbish, and seldom used for domestic use.  You would be better off getting a little electric heater form Argos, which will heat the room in minutes.  And get the landlord to pay for it!

Vicky

The main advantages of storage heaters are that for any given house they're generally cheaper to install than an equivalent central-heating system, and they require almost no maintenance (just check that the vents aren't blocked with dust).

The big disadvantage is that they are so uncontrollable.   In the depths of a cold winter it's not so bad, but when the weather is unpredictible -- cold and rainy one day, bright sunshine and 70 degrees the next -- it's practically impossible to anticipate the requirements and adjust them accordingly.   

Running costs can also be high in places which aren't well insulated or if you leave them turned up high and then have to open windows to compensate, although the overall difference in costs between electric and gas/oil aren't quite so great as they used to be at one time.

We had one in my old office.  When it started to get cold, it took 20 hours to heat up and heat the room...by which time it had got hot again and it took a day to cool back down!


Vicky

That's the problem with storage heaters.    You can't get heat from them until the next off-peak period (usually midnight-7a.m. or 1a.m.-8a.m.), so if it suddenly turns cold you have to resort to using portable heaters (which are more expensive to run).  If you crank them up in anticipation of it being cold tomorrow and then it turns warm, you're stuck with the fully charged heaters belting out heat that you don't need or want (even with the damper shut there's a significant amount of heat being dissipated). 

They'd be good enough through bitterly cold winters in extreme northern climes when you know you'll need the heat, but in unpredictible Britain -- especially Spring and Fall -- they're just not controllable enough.