We have a baxi solo 3 pfl 30/80 boiler-it appears to be working, it fires up and yet there is no hot water or?

it fires up and yet there is no hot water or heating-we have checked the water tank which is topping up normally, bled the radiators, we can't work out why its not working, all lights go on when you turn the knob and the pilot light is on, it makes all the right sounds any ideas