Had my boiler replaced 13 years ago under the the warm homes scheme back then or something like that name. Like everything else these days I don’t think they do it any more but back then I had a grant that covered up to £3K.
My boiler then was working the central heating with no problems but the HWS was suffering an intermitted fault that British Gas engineers could not pin down so suggested the boiler needed renewing. They sent around a guy who was over the Moon in telling they had this fantastic boiler on offer that only cost £750 then after 10 minutes of faffing with his laptop informs me I would need a boiler fitting kit then labour so in the end came to near on £3K.
When the guy came to fill out the grant form to pay for a new boiler he asked what was wrong with the old boiler and I told him the heating is OK but HWS is a bit hit and miss with it taking serveral minutes to warm the water up sometimes, and he said the same to “we can’t give you the grant if your boiler is working” but kindly said to me “sorry I miss heard you then but you did say the boiler was not working at all” and I of course said “correct its not working” and he put down on the form that the boiler was as dead as the Dodo.