My alpha 280e combi boiler is very erratic in terms of heating the hot water. When I turn the hot tap on in the morning the boiler doesn't light and there is no flow of water at all, not even cold water comes through. Sometimes when I switch the heating/water selector switch back and forward a few times, this seems to free things up and the boiler lights, with hot water following a couple of minutes later. This process can take about 10 minutes though. I am on a BG service contract and have had them out 4 times in the last 6 months. I think they must have changed every working part, but still no improvement. I'd appreciate any inspirational thoughts....Thanks