You have two lessons from this experience.
Never allow a seller to send you a 'replacement'. He probably never sent the original either. This is a recent but widespread Asian scam. We're starting to see in with Western sellers too.
Only accept a refund. If the purchase arrives after the refund, you can repay it using Paypal's 'Send Money' feature.
You have only 45 days to file a Paypal or eBay dispute for a refund.
However.
Go to the credit card you used to pay (PP is just the mediator) , call the 1-800 customer service number and ask about a chargeback.
Have dates, transaction numbers, and amounts handy to help the clerk process the refund.