you just open a claim, after 7 days and no response from the other person you then can escalate the claim-paypal give you the money back and then persue the person themselves!
of course the person who i was dealing with ignored the claim and i got my cash back, if he replyed saying he had sent the item he would have to provide proof of postage etc!!
then i would have to gather up all my evidence and email it to paypal