Dahon Folding bike, seat came right off! I was adjusting the seat on my Dahon Vitesse D8 when the seatpost quick release simply fell off (yellow piece in the images I supply)

The piece that bends to stop the seat from moving came off attached to the seatpost too.

I'm not so good at these things. No matter what combination I try there are always two issues (even when I successfully get the seat to lock in place)


The seatpost is constantly rotating (as opposed to completely locked in)
I can't pick up the bike by the seat, even though it's locked so it can't move down, it always freely comes up when I try to pick it up.


Here is a small gallery of images with my issue: 

http://imgur.com/a/9xKFV

I've tried all sorts of variations and cannot get the the seatpost to lock in place properly...

Any help would be great! I've tried downloading the manual for this bike, but no where are these pieces mentioned or even an assembly guide.
Looks like there's something missing.  The golden piece should go around the top of the black piece of the frame, and should clamp it tight without the two edges touching by the threadded bolt.

The silver piece looks like a shim or a spacer of some sort, and the seat and seatpole/post has not been pictured, but would go inside the silver tube.

Is there a second seat clamp (golden piece) missing, to go around the silver bit to hold it to the seat post proper ?

Edit:-
A google suggests these have telescopic seat posts, so silver piece is not just a static shim.   The other possibility is your seat clamp may have stretched and is no longer providing enough clamping force.