It should never have left the factory like that, even if it did the dealer ought to have sorted it out before delivery.
Agree that MMC should not have produced a car with a defective handbrake but if the engineering is defective surely the only thing the dealer could have done is sent it back to "the factory" as "Not fit for purpose". I can't see where a dealer is expected to rectify what appears to be a design issue rather than one of simply adjusting something correctly.
