If attempts to work with their customer service have failed then I would contact the credit card issuer (or PayPal if you used them) about disputing the payment. That may get their attention.
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I don't order a lot on line but this week I had a dreadful experience with Gene Bra. I want to return an item that THEY somehow placed on my statement. I did not order this item. When I called to inform them they offered me $7.50 to keep it. The item totaled $19.00, eventhough I have called back and asked questions and wanted a supervisor, the answer was the same. Do not order from Gene Bra on line, if you must place the order on phone..
Ilene