Towbar install and bits left over?

[onions]

Hi all,
I recently had a Hayman Reece towbar (trailer hitch for you US guys) fitted and when I collected the vehicle the installer asked whether I wanted to keep the bits that were taken off the vehicle for the bar to be fitted...

I of course said yes...but now I am worried as to whether all of these bits should have come off the car for the bar to be mounted...

The bits include lots of bolts, a long flat bit of metal and a two shock absorber looking things...

Your advice would be very much appreciated...

Cheers,

Ian