i am looking at retro fitting a 3rd rear headrest,when i went to the dealers i was told that it was smaller than the other two.however the price for the headrest are all the same.i would be grateful if somebody could tell me if they are all the same size many thanks.

The headrest is smaller, as for the price I wouldn't know if it should be the same.

It looks something like this:

But why do I have a feeling that it comes with the whole seat and not on its own?

Hi you can order all the parts separately did it with my last mk2 Fabia. You need the frame, foam, cover to match your interior, and guide tubes can't remember exact cost but it was about the same as ordering it from factory (£40 ish). Just need to be careful cutting holes in top of seat as the holes for the tubes should already be there if you feel along top of seat with your hand. Should be obvious which tube fits in which side. Will try and find old receipt with part numbers.