Zone Valves and Manifolds

Starting at the beginning, my mother (two years ago) had her boiler replaced, the installer left without the radiators getting heat (annoying but that is what happened), she had another two plumbers come who stated that her manifold was blocked but were to busy to replace it. She only made me aware of this last week s done some digging, her house is a Taylor Wimpey and after getting hold of their tech spec there is no mention of manifolds being used, the bore in a typical 10 MB, lifted the stair carpet and no access panels, of course this is new build so doesn't rule out a manifold. Today I discovered an access panel in her airing cupboard which housed two zone valves, one for the lounge and the other for the rest of the house, upon firing the boiler neither valve could be heard operating and both 14mm copper feeds were stone cold. I'd be very surprised if both had failed which leads me to a question, are they fused via a spur? The breakers are all ok and I can't see and fused spur in the vicinity, the loft maybe? I'm very hands on but boilers are usually left to the engineers, unfortunately none are interested in this job, and help or advice is greatly appreciated.