Worcester 24CDI request for manual no hot water in taps?

I have a worcester 24CDI combi boiler and I have 2 problems, firstly I have no hot water in the taps and secondly I need to close off the value under the boiler but try as much as i can it is always slightly off and the pressure boils up again to over 4 bar, i dont have a knob just a flat head screw and no markings , also has anyone got the manual for this boiler had the gas engineer out he was not sure of how to solve problem.