The buyer may simply not be on eBay, received item, left feedback, unnless she purchases more she would have no reason to come back to check messages.

BTW, emailing eBay will do little to nothing, you need to call them.

Looks like you are right, must be casual buyer, no reposne to message or feedback revision, oh well.  She is on my blocked list now, just in case she decides one day to come back to ebay and buy again.  Red dot hasn't caused me any issues anyway. Thanks for comments.   Merry Christmas and a Safe and Happy New Year to all.