Hi Mark, this might come too late for you, but perhaps may help others with the same issue. 
I had the same problem and initially I replaced the wrong thermostat....I replaced the thermal cut out (TCO) which looks very similar. 
The fan cooling thermostat is slightly different: for my model (S20 MX1) it was this part from shop.ukwhitegoods.co.uk - 
https://shop.ukwhitegoods.co.uk/818731204-cooling-fan-thermostat
(NOT the Safety Cut Out thermostat ) 
Hope that helps others who might have a similar issue
                
 Paul
                
 October 2021