Could you try phoning during your breaks?
If you paid through Paypal using your credit card, you can phone your cc's customer service and ask about a chargeback. Have all the transaction numbers, dates and prices handy for the customer service clerk. You may have to prove that the item has been returned or at least shipped back.
You can add a Response to any feedback, yours or the sellers. Like the most effective feedback, Responses should be calm and factual. Other members will judge you on your feedback as well as your seller.