Check the instruction manual and make sure you haven’t missed anything obvious, but otherwise don’t try and fix the problem yourself – it’s dangerous and you could make a bad situation worse.
Now what sometimes happens in winter is that the boilers outlet pipe will freeze and get blocked, which will stop the boiler working properly. Now this might be something you can fix - using a hot water bottle, say – but if you’re in any doubt, leave well alone.
The golden rule, when you’re having any work done to do with gas or electricity, is to only use someone who is registered as professionally competent to do the job. That’s the gas safe register for gas, and for electricity is one of the official competent schemes run by the Government.
Always ask the tradesman what scheme they belong to – check and make sure that they’re up to scratch to do the job.
Now all this strife and expense can be avoided, or perhaps just reduced if you take out a service contract for your boiler or your central heating
You get access to a qualified engineer, and you know pretty much in advance what it’s going to cost you. If you call someone out of the blue to do the work on the day the cost of getting your boiler fixed will bring you out in a cold sweat.