I now take back any suggestion that you refund anything, and I would have refunded less al fees only, as they are a twonk, ebay will not do anything and just reply to the dispute saying it was a pick up item inspected before being accepted.

Send them one last email telling them that there is absolutely no buyer protection for pick up items and you don't care how many opinions they get under Australian consumer law anything purchased second hand from a private seller is sold as is so they had better learn how to tune it or use it as a doorstop as it is not your problem.