If I had a hammer

Sooo. I sell stuff on ebay from time to time... who doesn't? At the moment I have a french chick really grating my ass about not receiving a package, this is despite the fact that it took a number of reminders and several days to inspire her to make payment, and now she lodges a complaint with PayPal for Non Receipt of item after only five days...
I don't know about you, but I haven't yet got hold of the beaming, tube, or the time/space temporal shift technologies to be able to instantly send a package from Australia to France! And sadly, I am also neither a blinky blinky noddy head jeanie, or a twitchy nose witch, so I must rely on the postal service (Auspost time-frames are 3 - 10 working days).
What I am most concerned about, since she has escalated the complaint further, is that I fear I am being conned. La femme did not pay for registered postage and therefore there is nothing stopping her from receiving the item and claiming it never arrived. I have no proof of postage, aside from a generic receipt that doesn't provide specific details of the transaction... merde!

Why are some people just ... jerks?