I have a Potterton Puma 80 boiler. It's not been on for about 3 months as was having work done to flat. I switched it on recently and it was working fine - heating and hot water - except external thermostat was broken. This didn't seem to affect the heating or hot water. Then all of a sudden it stopped working - no hot water or heating. I noticed that the pilot is not on. I have tried to re-ignite but it doesn't come on. I can see the sparks the igniter makes. Can anyone help?