If you and other sellers get together and hire a law firm ebay may make
some changes and maybe not but I can tell you who will be paying for
their lawyers (and yours) and I can tell you that's not ebay. *You* and
every other seller here will pay for ...
Tell your buyer they can open an Item Not Received case the day after
the latest estimated delivery date, and then if the package doesn't get
to them within 5 (or maybe it's 3) days after you will issue a full
refund.