Hey man,
I had one come off my drivers seat,
Was a bit confused when all the seat adjustment functions still works...
I think its just for comfort of the seat when your going over bumps etc,
Fitted mine back on yesturday, it's now a lot better.
Easy job to put them back in, but i did have my passenger seat in place as a reference!
The spring needs to face from front to back (not side to side), with the end with the plastic cover on towards the boot end. The hooks on the ends - the one nearer the plastic cover needs to face up, there's a little slot under the seat, near to the 'up and down' handle, takes a while to get it in correctly, then attatch the other end with the hook facing inwards towards the handbrake etc..
Just have a feel under the seat for a few mins and you'll see what i mean!
Cheers,
Jas