Hi sorry for the delay in responding.
Have you pressed the learn button on the received and the set button on the thermostat?
As both the receiver on the boiler and the thermostat need to sync and go into 'learn' mode to reconnect.
What is the model of thermostat, the RX1 is the boiler receiver model number
It sounds like there is a failure in one of the two devices, as a workaround for this evening you can press the CH1 button to manually turn on the boiler.
I assume your holding the thermostat right next to the boiler control when trying to sync the two of them?
If the manual override works, its most likely the thermostat has failed, what is shown on the display of the thermostat?
Ok, so if the manual override fails but your getting hot water its suggesting its the receiver at fault.
Press CH1 so the light goes off then press CH2, wait 2 minutes and see if the boiler starts (if it doesnt press it again to switch of the light) then press CH3 and see if that brings the boiler on.
Ok so you have a single channel receiver, I would be confident in saying you need to get a new receiver then.
There isnt an option to override the boiler this evening.
The new receiver can be picked up for around £55 online, which means you probably wouldnt get it for a few days if you ordered it from here. However if you want to get it sorted tomorrow you can buy a complete kit here from screw fix for around £120.
Replacing the receiver is very straight forward, turn off the power to the boiler first. Then you remove the two screws at the bottom of the receiver. To remove the receiver from the bracket lift the bottom out and up, that reveals the bracket where all the boiler wires terminate, if your buying the same receiver you leave the bracket as is, then slot the new receiver on the old bracket and do up the screws and re-sync and it should all work.
If the unit is still within warranty I would contact the company who installed it, as it should be able to get it exchanged for a reconditioned one at no charge. With regard to the wires, providing your replacing the receiver with the same model you do not need to touch any wires as the back plate can be reused, so you just un-clip the unit off the back plate and install the new one.
Good evening I just wanted to check if you had any follow up questions, and ask if you could rate the service received?