Am I to assume we are referring to a Domicompact F30B. Then you must have a top-up point somewhere.Do you have an expansion vessel/tank away from the boiler if so check there. Otherwise look at your c/h return pipework should be 22mm it returns to the right hand side of your boiler base follow this the cold water top-up hose will connect somewhere with visual ability to see the system pressure.Unless of course the "temporary" hose has been removed but your fixer should have been competent to give you a definitive analysis.
Guytawe
May 2010