Contact the credit card company through which you use PayPal. They'll cancel the charge. The seller, certainly, knew that a PayPal charge could easily be reversed, so be cautious about closing the door to a source you may want to use. This could have been a simple mistake. If the fellow isn't answering his phone, it's more than likely he's out of town. He certainly wasn't going to get rich on your $20.00 purchase.