Lover Come Back (1961)

Director: Delbert Mann
Cast: Ann B. Davis, Doris Day, Edie Adams, Jack Kruschen, Jack Oakie, Joe Flynn, Rock Hudson, Tony Randall

Synopsis:

Jerry Webster and Carol Templeton are rival Madison Avenue advertising executives who each dislike each others methods. After he steals a client out from under her cute little nose, revenge prompts her to infiltrate his secret “VIP” campaign in order to persuade the mystery products scientist to switch to her firm.