Same thing here, having the same issues with the transfer case leaking oil ... got told the same story from Mazda dealer that needs replacing (as it cannot be serviced), and at the same time the splines need to be checked. Up to $19k if has damaged gearbox.
Have contacted Mazda Australia and explained all the details that this started at around 88k mileage (vehicle was just over 6 years old at the time), but they proceeded to waste my time and in the end tell me they can't do anything.
The ACCC path might be the way to go, as the product has a major design fault (failures) which is being ignored by the manufacturer (it sounds like this is common for these models).
Might also be able to go after the dealer that sold this, as they are also obliged to call out these issues.
Found this article from ACCC:
See Table 2 (page 24) - Major and Minor Failures
Major failures - These cannot be fixed or are too difficult to fix within a reasonable time. A failure is major if:
• a reasonable consumer who was fully aware of the nature and extent of the failure would not have bought the vehicle, part or service, or
• the failure prevents the consumer from using the vehicle, part or service for the purpose that vehicles, parts or services of that kind are commonly supplied for (or for a purpose they disclosed to the supplier before purchasing), and it cannot be fixed within a reasonable time, or
• the vehicle, part or service is unsafe or creates an unsafe situation.