Well I have had a similar case but it was only for about $80. So, I bought my camera lens and it was not as good(some defect that wasn't stated) contacted buyer,,same thing like yours sent me a return label, but no refund......same case with you..............till that response from ebay. I then contacted paypal and show them all the evidence including ebay's response. Paypal contacted that top rated seller,,,,,,seller responded me back and apologized for delay,,,gave me my refund. It took abt a mth though to dismiss this case.
PS. if it was a credit card check with your bank since lot of credit card cover those kind of things these days. My chase slate does.
Good luck bro