James,
I had my drivers seat 'refurbished' a year or two ago. The bits that hold the springs were broken, but they were relatively easily fixed by the seat guys. They re-did the padding and it made an enormous difference, but is probably a way away from being fully re-done. That's for another year. (150 euros for the work they did, versus 500 euros for a complete rebuild with new pads, etc).
JH