Great... You are in luck. If you use PayPal to pay for something you buy on ebay, you can open a Dispute case on your paypal account. You select the transaction in dispute, and then it will notify the seller that a dispute has been opened. You can then send messages to the seller through paypal. the seller will reply to all your messages. Once a case has been opened, paypal gives you a 2 weeks or so to resolve the case.
If you and the seller don't come to some sort of agreement, you can simple click on the "I would like to end communication and escalate this dispute to a claim with PayPal " and paypal will review your case and if they favor you, then PAYPAL will refund your credit card, and claim that money from the seller. It's as easy as that!
Go into your paypal account right now, Click on Resolution Centre -> View Open Cases -> Report a Problem.