ebay feedback question

I filed a NPB (no paying bidder) complaint against a buyer as she had not paid 5 days after the auction ended. She then paid, I shipped her the purchase, she left me neg feedback with very rude language. I have contacted her about explaining reasons for her feedback, she apparently ignored my emails.

questions:

1. Why doesn't eby block NPB from leaving feedback?
2. What can I do to resolve this if she chooses to ignore my contacts?

I also saw she left the same bad feedback against another seller.

my feedback rating has been 100% for the past year. very upset on this

Thank you