ShipScript has been an eBay Community volunteer since 2003, specializing in HTML, CSS, Scripts, Photos, Active Content, Technical Solutions, and online Seller Tools.
The seller must use a feature on his own feedback page to request a feedback revision. eBay will send that request to you to act upon. So, if the seller has not yet requested a revision, you can ask the seller to start the process through eBay.
https://www.ebay.com/help/buying/leaving-feedback-sellers/viewing-changing-feedback?id=4031#section2
