Danny was amazingly helpful - explained the process clearly and was extremely patient when we needed - frequently- to start again. If he does this all day, I think he deserves a pay rise. I now know, and have written down, things I was probably told when the heater was installed but didn?t register at the time. It was perhaps unfortunate that the only leaflet accompanying the refurbished thermostat was for the control unit, and I don?t seem to have thermostat instructions in my original paperwork from 2015. It might also have been helpful to indicate the unit was sent out without batteries. Especially, clear instructions needed on how to open the unit - once you know it?s obvious of course, but..... But - Danny had saved the day! Thanks again