boiler broken down cant find parts
If you know what and how to fix it, then get the model number and GC number, goto your local Parts Center and they usually help you out.
If not, go onto Corgi's website and look for an engineer near you
what is the strange groaning noise coming from my central heating boiler?

If you know what and how to fix it, then get the model number and GC number, goto your local Parts Center and they usually help you out.
If not, go onto Corgi's website and look for an engineer near you
References :
As mentioned above the best place to try is your local parts centre (HRPC), they should be able to get the part you require. Failing that, get in contact with the boiler manufacturer, they probably won't sell you the part direct but I'm sure they'll be able to point you in the right direction.
References :
HND Plumbing and Heating (North Wales)
Call a corgi registered engineer, they will source and install the parts for you, you are likely to have misdiagnosed the fault, in which case you will be paying twice.
References :
Heating engineer