eBay's dispatch / delivery information is always slow to update, but to show delivery, eBay only works on tracking showing delivery, not from any say so from the seller.
If tracking has not been provided to confirm delivery, open a case for item not received, and escalate on day 4 if not refunded beforehand.
If the seller has tracking to show delivery it will close the case with no refund, and here, you'll have to ask the postie or courier used, as to where the item was left, it may even be in your local sorting office awaiting collection.