It is illegal for paypal to hold funds for change of mind or remorse return reasons under Australian law.

They are well aware of this.

I suggest that if this is the case then you contact paypal and politely ask them to release the funds and if they fail to do so then you should file a formal complaint with the FOS.

If the buyer has claimed it is not as described, either by accident, or deliberately, then you will need to get them to admit that is not the case and close the case for you from their end.

If they fail to do so but don't escalate it and otherwise ignore it, then as other posters have said it will eventually time out and the funds will be released.

If the buyer has claimed it was not as described deliberately, when that in fact is not the case, then the buyer is guilty of fraud and you can pursue that. Sometimes simply pointing this out to the buyer in a message is sufficient to get them to close the case.