The Evohome Shop have an offer on at the moment.
If you buy an ATP921R3100 Connected Thermostat Pack with the HR924UK Radiator Controller 4 pack, they’ll give you an additional 4 pack absolutely free.
https://theevohomeshop.co.uk/50-xmas-pack-deal, add both the ATP921R3100 connected thermostat and the HR924UK radiator controller pack to the basket and a second HR924UK pack will be waiting for you at the checkout.
Offer only applies to their current stock (around 55) sold on a first come first serve basis.