@Gibraltar, this fault, which I believe is defined within a service bulletin since it seems to be a know fault, should have been fixed as a matter of course whenever the vehicle presented for service. The fact Holden didn’t do just that is indicative of why they are not #1 and indeed closing shop. Otherwise it should have been fixed as a (factory or ACL) warranty item.
Also a wobbly seat is easily seen as a safety issue, which would defect a vehicle if seen by police. But why it wasn’t a safety recall I have no idea
And safety recalls aren’t bound by time, just look at the Takata vehicles being recalled
So, if the dealer plays hardball, you could remind them it’s a safety issue and likely a major fault under ACL and you’re within your rights to chose the remedy under your statutory warranty.
Then tell them you want it fixed. If they are clued in, they will fix it all under your statutory warranty and the clips and labour won’t cost a thing