Jens... ebay cannot by law find in favour of the buyer if proof of lodgement can be shown by the seller. See below.

If they do then it will be overturned by the ACCC upon lodgement of a complaint, or the FOS if its done by PayPal.

Here is a quote (direct copy/paste) from the QLD SOGA...
Each state has its own SOGA but in this regard they are all the same in Australia. The relevant section may not be the same in all cases.

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SALE OF GOODS ACT 1896 - SECT 34

34 Delivery to carrier

(1) When, in pursuance of a contract of sale, the seller is authorised or required to send the goods to the buyer, delivery of the goods to a carrier, whether named by the buyer or not, for the purpose of transmission to the buyer is prima facie deemed to be a delivery of the goods to the buyer.