Here in England the course of action would be clear: legally, the dispute is always between the customer and original vendor. It's legally of no concern where the vendor sourced the products from, the vendor is obliged to replace / repair / refund in the event of a no-fault warranty claim. Your country has first-class after-sales service chiselled into your statutory law including the best statutory warranties in the world, so I'm pretty certain, even without knowing the intricacies of Australian law, that your dispute is also with the vendor, not with the importer.
Having got the vendor to accept their liability, I suspect the problem is then going to be that the vendor will dispute that this is a no-fault claim. i.e.: as sure as night follows day, I can anticipate they will say the water damage was caused by you. I'm not sure how you disprove it. But equally, I don't know how they can prove it was you: they can only prove the water damage exists (which I note you said they still have not).
A threat to see them in small-claims court usually settles matters in your favour albeit unamicably, seeing they won't want the negative publicity, hassle or costs.