DO NOT REMOVE THE NEGATIVE FEEDBACK UNTIL YOU HAVE THE MONEY!!
Since you do not want the expense of returning the item to the seller (China? This kind of demand is common from scammers there. And in fairness, elsewhere.) your only card is that feedback.
When you have your money back, you can call Customer Support and ask for help.
But not until your full original payment is back in your Paypal or credit card account.
You have only 45 days to file a PP claim, but if you actually paid from your card, the deadline there is much longer and they may agree to the refund without the return.