Car is hitting 90,000km so yeah it's probably wear and tear.
I did 200,000 km’s over 20 years in my Mazda and everything looked new inside and out with absolutely nothing wrong with the seats front or back. Sadly the car was written off by some idiot
So from my Mazda experience i’d say foam collapsing at 100,000 km’s is not ‘wear and tear’ but poor material choice and construction. Seems that’s a common denominator with Holden
So who did the rework on your seat, a Holden dealer or someone else? What did they actually do, take the seat out and do a reform on the drivers side bolster?
If the seat ‘pain in the bum’ issue occurred after the seat rework, best to take it back to who did the work as get them to look into it
Hope I have better luck with my MSE than what’s seen by most Holden vehicles (Though the glue failing on the material strip on the bottom leading edge of the sunroof and on the underside of the wheel cover makes me think i’ll have fun with the dealer - not)