To onion_soup:
Don't know any info re charges, 24/7 etc as I don't need to take out one of these plans as I fix my own boilers. Any problems fixed on 1st call out will be the simple little things such as low system pressure, anything requiring parts will probably require a return visit unless you have a Vaillant and go with the Vaillant plan,whereby they will probably stock things like NTC's , pumps & the dreaded diverter valves for some of their own boilers in the vans.
To Ollski
Vaillants tech help is as good as any other manufacturer, i.e rubbish. This should be no reflection on their engineers. I don't know any engineers who use the tech help for anything, you will find better help asking professionals on this forum! BG may have fancy laptops with boiler instructions on them, but I've only been in this industry for a couple of years and I've been and fixed 10 or more boilers that BG have came and scratched their heads at, usually quite rudimentary problems. BG will not cover your boiler once it gets past a certain age, they just seem to say that parts are no longer available and your plan has to be cancelled if you don't take a new boiler. I've seen this a few times too.
With independants, their service plans are usually alright IF THEY ARE A DECENT COMPANY. A local company with a ****poor reputation will have a poor quality service plan, a decent local company with a service plan will probably be OK to go with.
IMO if the man has a Vaillant boiler he should go with their service & breakdown plan, if he wants a service & breakdown plan. How many Vaillant models in active service in this country? 30 maximum? If their engineers are visiting boilers day in day out with a maximum of 30 different kinds then they should be pretty proficient in every one of those models in quite a short period of time, eh?