They sell a kit to repair these seats. The first time I paid and watched a guy who does custom interiors, next time I bought a kit and did it myself. It is not all that hard if you have seen it before. Basically, you have the metal part of the seat which is comprised of springs on some, metal looms ( at least I call them that), the outside metal frame. Then it is the foam top and bottom. Then the seat covers, or the material that covers them.
If you have a problem with the internals of you seat, once you get it apart you will be able to see how easy it is to repair or even make it stiffer if you want.
Basically search u-tube or the internet and watch a video on how to do it. Then order your kit, and take a Saturday and fix your seat. Really not that hard. Good luck and keep us posted.