Even the endlessly talented and infinitely adorable Isla Fisher cannot overcome the script problems in this unfrothy romantic comedy about a writer who just can’t stop shopping. As hard as they try to make her irresistable, the character she plays is careless, thoughtless, and untrustworthy. And yet, everyone in the movie seems to be utterly won over by her, making the disconnect between the reactions of the audience and the reactions of the characters more and more jarring.

Fisher plays Rebecca, who was forever blighted by her parents’ penny-pinching. She wanted sparkly and colorful but her mother always bought brown and sensible. So she has grown up into a woman who cannot resist that most magical of siren’s refrains: “SALE.” They are not kidding about the “aholic” part of the title. Like any addict, she is in denial about the way in which her addiction has affected her life and the lives of those around her. She mooches off of her best friend and roommate (a delightful Krysten Ritter as Suze) and constantly lies to everyone, including herself. She goes to great lengths to avoid those nasty people who keep calling her because, oh yes, she does not pay her bills. It is supposed to be charming and funny that racing to the interview for what she says is the job of her dreams she is waylaid by a $120 green scarf, which she pays for with a combination of cash, several credit cards, and what amounts to attempted check-kiting that turns into a straight-on con, based on a gabbled story about a sick aunt. And who turns out to be on the other side of the desk in the interview? Yes, the con-ee himself, the handsome editor (Hugh Dancy in another Prince Charming role as Luke). An all-star supporting cast includes Kristen Scott Thomas as an imperious fashion editor and Julie Hagarty channeling Miss Jane from “The Beverly Hillbillies” as Luke’s assistant.

It is always a mistake for a movie to be more in love with its heroine than the audience is. A little romantic fantasy is welcome but here it reaches absurd levels as the most selfish and irresponsible behavior by Rebbecca produces coos of ecstasy from everyone. She instantly becomes an international sensation with a frivolous article using shoes as a metaphor for personal finance. And preposterously, when she finally begins to accept some responsibility for the mess she has made, the movie wants us to be on her side when she undercuts her inexcusably overdue payment with a silly prank. Fisher should have shopped around for a better script.