2.) pop to vauxhall and order a set of mounts the same as the front seats.
3.) feel about the tops of your rear seats you should be able to feel the holes around the middle of the seat these were fitted into all vauxhall rear seats they are about 1 inch under the fabric so poke around quite hard.
4.) using a stanley knife make little holes in the seat fabric where the holes are, big enough for the mounts but dont over do it as your seats will rip.
5.) Cut the little plastic clips of the mounts with good old stan.
6.) Push a mount in each of the holes until they are right in flush against the seat (it may take quite a bit of force.
7.) fit headrest into mounts adjust height and live happily knowing that anyone in the back will be less likely to get whiplash in the event of a crash.................