I’m not in a position to guide you around the financial aspects of this problem, Joseph, but it remains that the transfer-case in this model Mazda has, indeed, earned a very patchy reputation. It seems that Mazda never specified an oil-change interval for the transfer-case and, over time, the oil can break down and lead to high operating temperatures and internal wear of the mechanical parts. This can include metal fragments breaking off and damaging other components, as well as the high temperatures causing fusing (damage) to the metal parts. In some cases, that can also damage the spline shaft that joins the transmission to the transfer-case and, if that happens, the transmission will also be severely damaged. This has been known to occur in cars with as little as 70,000km on board.
The reason the transfer-case oil wasn’t changed when you had the car serviced is simply because that task is not listed as a service item for this car. Which was, remember, the problem in the first place. Most workshops now agree that the CX-9’s transfer-case oil be changed every 60,000km or so, but sadly, it seems that’s all a bit too late for you. There was a Special Service Bulletin issued for this problem in the USA, but don’t assume that this will also apply to Australian Mazdas. That said, I’d still be having a chat with Mazda Australia’s customer service department.