Can anybody recommend someone to service my boiler? My dad messed about with the timer thing on it which doesn't actually work and since then if i put the boiler on summer mode (so the central heating is off and i just get hot water) the light often goes out. Also i can hear the heating system, it's like a very faint hum. I can hear it more upstairs. It's not insanley loud but it's certainly noticabale.