17421 is a replacement style for a style in the same silhouette, but different fabrication (style 17370.) Is it possible that you are comparing the two, which differ a bit in inner construction and type of powernet used? If so, it is possible the two fit slightly differently or provide a slightly different degree of control. To address your desire for firm and extra firm shapewear----Annette will continue to provide these garments, via HerRoom website to the consumers who desire more structured control garments.
Ms. Vea from Atlanta, GA