Okay i got the st24 interior, now the bolster on my right leg i think is collapsing, what with me being so skinny n putting my weight on it everytime i get my rather large behind out, i think its bent!!
If it's just callapsed and the material is ok, then I would suspect the the metal frame which supports the leg bolsters has come away from the seat base. Normally you can bend it back.
It is possible to take the seat out, detach the back rest and remove the seat cushion. You will then see the metal frame on the seat base. This is normally held on with pop-rivets (mine were). If this is the case then you may be able to rivet it back on.