Give the seller 24 hours to respond. Perhaps send a follow up message attaching a photo of the vases (if you haven't done so already) so the seller has evidence that the vase was actually damaged. Unfortunately there are some dishonest buyers and sellers around that make false claims, so a photo will at least assure the seller that your claim is legitimate.

If the vase arrived damaged then I believe the seller should refund you for it (as well as the postage associated with it), or send out a replacement. Irrespective of their terms, you are entitled to receive a vase in the condition as shown and stated in the listing. Australia Post have a policy of not being responsible for damage to fragile items sent in the post, so sellers need to exercise caution when packing fragile items. In saying that, sometimes even the best packed items can arrive damaged as I have received parcels myself that have been squashed/torn apart with a note attached from AP stating the packaging was damaged whilst in their possession.

It's also a good idea to mention in your communication to the seller how you expect them to resolve the matter ie refund or replacement. I hope you reach an amicable resolution with the seller.