if the property meets the exemption criteria for needing a HE boiler it is possible to fit an SE boiler in a swap over in 3-4 hrs so if you can buy a boiler for £400 odd, then yes it can, or if an HE is already in then how long would it take to sway a boiler for an exact same model? we used to do warranty work for various manufacturers and got 3.5hrs labour to change a boiler, ok you use the old flue hole and existing jig so again yes it can, obviously anything else needed gets more cash, how you do you sales pitch is up to you, this is how they do theirs, from the landline they must be in Bellshill area a few miles from me but i dont know them, nice free advert you are giving them by leaving the phone number in!!!!!!!!!!!!