RE: "funds may be withheld for 21days"

Paypal should not be withholding funds for items sold via ebay (or any other source). If you email them stating that they are to cease withholding your funds immediately and that all interest on the amount withheld be credited to your account, as it is illegal to withhold access to funds within Australia. Also stress the point that you are prepared to take this matter to the Financial Ombudsman Service if your funds are not released immediately. Outline your disappointment with their actions towards a loyal customer. (Please note that they release the 21 day hold on funds and no further holds will occur, however will not credit you any interest).

Good luck 🙂