vaillant 242 eh combi/boiler leaking at the b t m.john?

please can anyone help me the heating engineer told me that my d. h. w.heat exchanger was leaking water also myflow valve, new part unabtainable,ref mini expantion vessel. he said l reg,ed a new boiler the boiler runs well can any help me get the parts at agood price and possible put me touch with agood heating engineer in the bristol area thanks. The part at the top is how the heating engineer put it down on his report.