As much as Holden states that afterblow will remove mold smells, that’s not fully true as all afterblow can really do is stop mold growth from taking hold (and with no moisture mold dries out and flakes off to be blown around the vehicle - yuck).
If someone already has a mold smell in their cabin and it’s due to water inside the cabin, it will need considerable effort and cost to identify and fix. As such there shouldn’t be any thought of ‘hope that Holden will come to the party’ as there are known causes that Holden decided to handle via service bulletin on complaints to the dealers. They didn’t want to correctly address these known failure (which can only be done by sending letters to owners).
As such, if I had mold smell inside the cabin, I’d be looking for the source to be identified. This would require carpets and any underlay being taken out and inspected for mold and evaporator and ducts to also be inspected for mold. If mold is found, I’d expect any water ingress point identified and remedial action taken to stop further water entry. Then any and all mold and it’s spores must be killed via chemical wash (which in the case of mold on evaporator and ducts is a very big job to do correctly). I wouldn’t accept some simple spray in the duct type remedy. And if mold was under the carpets, I’d expect new underlay and carpets installed as it’s next to impossible to kill mold within carpet and underlay.
I’d expect this would be on Holden’s dime as there are known issues causing mold. And since there is no legal requirement to service with Holden, and they took no action to notify owners of these defects, they should be paying the bill.
I’d expect no less from any manufacturer.