Boilers are very clever, they know when to shut off. In current freezing weather conditions the most common fault on condensing boilers is the condense pipe going to outside freezes. As a result the boiler will shut down.
The first step to fixing the problem is to poor boiling water over the condense pipe outside to defrost. At all times be careful not to scald yourself.
Once defrosted reset the boiler or turn it off and on again. Hopefully this will return the boiler to normal working mode.
If the problem persist, please give Sureway Heating Services a call on 01926 310900 and we will be happy to help.