I managed to fix my neighbour's boiler (re-pressurise). I had bought two of those metal service handles for the Vaillant boiler as one of the original plastic ones had fallen off and was missing. She didn't want to replace the one remaining plastic one as everything is now working well so I said to ask her engineer to swap them when the next service is due. She doesn't have it serviced! I said that I thought that this could affect her house insurance but I wasn't sure - am I correct? I did explain why the boiler should be top of the list for annual inspection. She owns the house, it's not rented.