Last winter you replaced my boiler and since then I’ve had certain problems with it, eg an intermittent loud hum coming from the airing cupboard which could be heard from the lounge despite the television being on. Despite call outs resulting in visits by different plumbers, until today this had not been rectified and I was given various reasons for this noise, none of which were correct. Luckily the plumber who attended today saw where the problem was and, after phoning the boiler manufacturer, corrected the error at long last. He also took the trouble to set the timer as I asked and explained how it worked. Very impressed with him!