I can certainly see your dilemma, Freddy. If only the spring was just about here, you could get on with the replacement rather than the repair without time and comfort being 'of the essence'.
It must sound like a hollow offer, but I rather wish that the limitations of geography and time did not preclude my practical assistance to you 'on site' for a week or so. I'm sure that, between us, we could get all that old and new pipework sorted out and the new boiler in and working before your fingers and toes went completely blue. That is, of course, if we could each tolerate the other's particular (peculiar?) ways of tackling the various tasks! (My wife will be glad to provide a glowing reference as to my mild, co-operative and flexible attitude to work, and life in general. See separate correspondence on that point on this board. )