I would leave it as it is, the only reason I questioned it was because you said you had to fit a pump in the airing cupboard and run a cable. So why do you need to run a cable? It should all already be at the boiler?
Sorry perhaps I worded it wrong, Pump is in the airing cupboard wired to wiring centre, not currently wired to the boiler.
Customer is away on holiday for 2 weeks from today so will have a quote sorted for when they get back.