I have a Worchester Hiflow 3.5 Combi free standing boiler which has developped a fault and ws wondering if anyone had any brainwaves on what is causing this? hen you switch the boiler on and light the pilot light the pilot light stays lit for about 45 seconds then goes out. This happens whether the heating, water or both are on or off. When the pilot light is lit it is only the pilot that lights, not the burners. Any help would be appreciated. My husband cn manage simple tasks obviously if too difficult will have to rely on experts or get nw boiler!