Hi . it could be a couple of things
Knowing the biasi though it sounds like the thermistors( temperature sensors ) have failed .probably the heating one .
They are about 30 pounds each and can be tested with a multimeter on ohms
Does the ignition fire up for a few seconds?
Things to check . does the boiler fire? Are you getting any heat , feel the pipes at the boiler .can you hear sparking, ie trying to light ,should be able to hear this
Yes ignition fires up for a few seconds
the radiator pipes gey tepidly warm as its igniting then cuttin out and repeating this process
Hi . pretty sure its going to be the thermistors . pretty easy to change once the waters isolated . shouldn't be an expensive job . you could do it yourself
Ok thats great will try they sell on ebay £6.49 cheers