I no longer trust Australia Post as I lost $1.000 worth of items sent registered post and paypal found against me on all four items.despite various forms of registration.

You must have defended the claim incorrectly for that to happen on Registered Post items. Paypal can't resolve a claim in the buyer's favour when the seller provides proof of postage, that is a buyer doesn't meet the eligibility criteria to make claim for items not received when the seller holds proof of postage.