[Duncan]

Pity you can't actually buy one from them!

You could try shopping around. Google found me http://www.autovaux.co.uk/ which says

We carry over 5,000 stock lines and can source any current Vauxhall Opel part that you would normally only think available from a Vauxhall, Opel , GM , Holden or Chevrolet dealer. These Vauxhall parts are normally available within two to three working days.

As not all of our stock is on the website yet, if you can't find what you are looking for please fill in a PART FINDER ENQUIRY

I've no idea if they can actually find the parts, but it's probably worth trying.