It was the gourmet chain that sought to swallow Manhattan: British sandwichers Pret A Manger arrived on our shores in 1999, aiming to pummel the likes of Cosí and Au Bon Pain. There were multiple mentions in the Times, 3,683 words of hype in The New Yorker, and lots of taunts from nervous rivals. Last year Gramercy Tavern pastry chef Claudia Fleming was brought on as food director to much fanfare.The trouble is, New Yorkers aren’t biting. The chain has shut down three of its sixteen stores, and a plan to have 40 outlets in New York by 2004 has been shelved. CEO Andrew Rolfe insists Pret’s not packing it in; it’s just trying to figure out what the city prefers on bread. “For instance,” he says, “we’ve had mayonnaise issues. Mayonnaise is quite popular in Britain, but Americans aren’t so receptive.” (Especially not New Yorkers.) A mayo-free line debuts next month. There was that no-soup problem too: “New York’s colder than London, so it makes sense you guys like it,” says Rolfe. “No one said this would be easy.”