I feel your pain, it's a real shame that to all CHR owners. Have you tried the ACCC for a warranty claim based on a major failure even out of warranty ?
The other suggestion is to change the oil far more often, like every 3,750-5,000 kms, especially if the engine gets less than 30min non-stop hwy/fwy driving at 80km/h or more at least once a week and/or does lots of short driving stints which causes the oil to quickly become diluted/dirty. These nasty oil vapours eventually finds its way to the air intake runners, tops of valves & piston rings caking everything up essentially ruining it's smooth operation - a bit like having cholesterol in your vains.
This clip explains it well . . . . https://autoexpert.com.au/posts/can-additives-clean-my-direct-injection-engine?rq=direct injection