Bon Ami works well to remove haze on older windshields but I doubt it's abrasive enough to remove physical scratches. If you can feel the scratches as you run your fingernail across the sufrace then you really don't want to polish/buff them out because your view out will be distorted as the outside surface will no longer be parallel to the inner surface.
Unless the scratches are really bad, just keep the glass as clean as possible and live with it until you can justify a new one.