First contact the seller and explain the problem.
There is a Contact Seller button on the listing.
If that is not helpful (and return the item to China is not helpful since with the necessary Delivery Confirmation you are looking at a postage fee of $40 or more), go to the eBay Resolution Centre and open an Item Not as Described dispute.
The first step there is to contact the seller , but will already have done that.
In addition to eBay, remember you also have the credit card you really paid with when you backed your Paypal accoutn with it (PP is just a useful mediator.) Go to eBay first, but the 1-800 number on the back of the card is a fallback. Ask the customer service rep about a chargeback.
Some cards will and some will not want you to return the item. Some will accept proof of shipping.
