Costs for fixing a diverter valve will sit around £250-350. Our free in-home estimates allows us to assess the kind of work we have been called to do the nature and size of the job at hand determines how much we charge you at the end of the day we do not charge you any extra fees like most other plumbing service providers are fond of doing. Document object identifier (doi): 10.3386/w23213. Visiting address: johannesfredsvägen 7. Participants.