If you opened a case via the eBay Resolution Centre and you still haven't received a refund by the time you read this response then if you have not already done so escalate the case to eBay so that they can step in to make a decision. You get thirty days from the date that you opened the case to do so - if you allow the case to time out then you will not be able to escalate it to eBay.
If the seller has not voluntarily refunded your money and case hasn't timed out yet then go back to your My eBay page and escalate the case to eBay straightaway. So long as the tracking number shows attempted or successful delivery to the address provided on the eBay Returns Label you will receive a 100% refund of the money that you paid to the seller. Therefore, ignore the seller's claims that he/she has not received the item and escalate the case to eBay so that you can get your money back before you run out of time to do so.
In the event that you have run out of time to escalate the case to eBay then contact PayPal about the matter. PayPal give buyers a maximum of one hundred and eighty days to open a case against the seller, so you should have plenty of time left to do so. However, you cannot open a PayPal case if you already have an eBay case open - therefore, only open a PayPal case if the eBay case goes against you or if you inadvertently allow the case to time out. PayPal tend to look into cases far more closely than eBay do, so once they put a trace on the tracking number that was given on the returns tracking label they ought to refund you in full once they see that the tracking confirms attempted or successful delivery of the item back to the seller.
