Dimplex storage heater spares

[Newlands]

Can anyone help with these? I think it’s a thermal switch. The live comes in on the right, through the first one, onto the second and then to the thermostat upper right, after which it disappears off to the heating elements. The problem is that the one on the lower left has slightly suspect* spade connectors which don’t always show continuity. It’s got a number on the back of it A/ 159-20 8617, and on the front it says Honest-Well T23.
I can buy several different varieties of this component on eBay, but none with the same 159-20 number. I think the 159 relates to the temperature, but 159°c sounds way too high for a storage heater. Can anyone suggest a substitute and suggest what sort of temperature is normal for a storage heater?
The first one, on the right, is a M/ 170-M1 7912 for what it’s worth. Why two in series though? Is that just extra safety?

* More than slightly now, I’ve just broken the f@&#£+ thing off. To be fair it was only hanging on by remains of a tiny spot weld, so it was never going to last.

 

[Pigeon_Droppings2]

Does the cap unscrew...maybe there's more info inside? Or maybe the spades could be replaced on their own.

 

[Milkybars]

CapriCalvert - nightstore heater parts ....

 

[Kayos]

One will be high limit so may be higher than expected, only designed to cut the supply if the other stat fails

 

[brightspark]

,bypass the dodgy one . if the adjustable temperature one fails the round safety one will cut out still ,even if it overheats you will soon notice used to repair loads of them it was mainly a thermostat and a fusible link to replace

 

[Newlands]

I can’t see a way of sensibly dismantling it - it looks like the back is crimped onto the ceramic housing. Soldering the spade terminal back in place is not going to work at the temperature the switch is rated at. Capri Calvert looked promising but they don’t seem to stock this sort of thermostat switch. I initially thought it was made by Honeywell, not Honest-Well (and yes, that’s probably what I was meant to think!) and Farnell do a range of Honeywell thermostat switches like this so I can probably just buy a couple of them - bit pricey though, around £25 each.
I’m still surprised at the high temperature rating though - is that normal for a storage heater? It would explain why things are a bit crispy inside the front panel I suppose.