Technical 2005 UK GP 1.3 90bhp Rear Suspension Bushes

[Appierre1]

I recently changed the rear suspension bushes on my GP with Powerflex replacements. One came out as in a YouTube video - https://youtu.be/XW6R1BTtrmU - on a similar Vauxhall. The other one proved more difficult, particularly the three bolts for the part that attaches the suspension arm/main bolt through the bush to the body of the car. When putting the three bolts back one sheared off the captive nut and I wondered if any one knows if the nut is accessible and simply under the interior trim and not hidden?
Thanks

 

[GrandePunto PL]

Under the back seat. Punch (with your finger) sound proof black material, seal, whatever it is.
Not much "access", but you can see all 3 nuts.

 

[Appierre1]

Brilliant photos GP PL many thanks, as was not certain where to make holes. Kind Regard P