Negative Feedback

[karenm7078]

I recently sold two blouses and accidentally sent them to the wrong buyers. As soon as it was called to my attention by the first buyer, who purchased and paid for a $20 item, I immediately issued a refund, and contacted the other buyer who received the item in error. (The second buyer purchased a $3 item). The second buyer wanted to keep the "wrong" blouse, laundered it, then reluctantly returned the item. She was also issued a full refund for her purchase, and sent postage for returning this item so the other buyer could have it. After she (second buyer) returned the item, she messaged me that it cost her more to send it back than it cost me to send it to her (???} and that I owed her money. She told me she would send a receipt and I told her I would gladly reimburse her for the difference. Instead of emailing me the amount, she told me she had decided to give me negative feedback. She left feedback stating that after sending her the wrong item, that my attitude was "insincere", "a mistake.". I did make a mistake, apologized for it, and refunded her money. I thanked her for being cooperative. Is there a way I can get the negative feedback removed?  How can she say that I had an "insincere attitude", and "be careful"???   Any thoughts? Thanks