I think you are the Buyer?
Who or what is 'it'?
Did the Seller tell you that he could not completely fill your order and then refuse to refund the over-payment?
Or was it eBay? Or some random email?
If so, that's bushwah.
Go to the Resolution Centre and open a Dispute as Item Not Received (or possibly Item Not As Described depending on the details).
You will be told to contact the seller first, but I think you have already done that (?) so go to Step Two and escalate to a Claim.
More details might help with your strategy.
