An update on this. Evri don't have any means of me asking for a non-delivery document which is what ebay are demanding. Evri have sent an e-mail in which they effectively shrug their shoulders and pass me back to the seller.
Seller is saying "Evri says it was delivered, so bugger off". Ebay are saying "Evri says it was delivered, so bugger off".
Fed up to the back teeth with this.