Allegations that Christie's auction house sold fake wine "over decades" have been made in a New York court.The complaint has been lodged by an American billionaire industrialist, William Koch, and is the latest salvo in a three-year battle that has embroiled Christie's and the leading British wine expert Michael Broadbent, a former director of Christie's and auctioneer who also wrote sales literature.Mr Broadbent has already won a libel action against the publisher Random House, which published Mr Koch's allegations in a book about the dispute.