Hi @[deleted],
I think the following diagram shows what you are after.

No. 21 - CLAMP,NUT,4.8,PROTECTIVE COVER FIXING - part # 11086793
No. 19 - SCREW,TORX,4.8 X 16,PROTECTIVE COVER FIXING - part # 11093171 (if you require any more)
These parts fit numerous models - (Astra G, Zafira A, Vectra B, Omega B, Meriva A & B, Corsa B & C and Tigra A) so should be available at dealers.
Hope that helps! 🙂