So a buyer buys £18 item from you. Waits for it to arrive then bypasses ebay and paypal by going straight to credit card company to say they didnt make the purchase. Paypal take back the £18 plus another £14 chargeback fee. What can be done about it. Have emailed the buyer to threaten police involvement but will they really be interested?
You only need to provide PayPal with proof of postage, and unauthorised use means just that, someone used your buyer's account without their consent - so who are you going to report to the police?