ive just fitted a halstead ace boiler condensing boiler, i also fit a plume diverter 135 degrees angle which fits on the flue gas terminal point.The part was a halstead make, the part cost me thirty two pounds . I was in a plumbing shop before this and a plumber bought the exact same part with a potterton part no it was over 90 pounds.So why the difference neither halstead or potterton could tell me why the high price difference