The whole thing didn't sit well with me. Producing a label for a 'non-return' was illogical. Went back to ebay live chat. Spoke to an agent - who advised ti request the label etc for buyer'. I insisted as this was a  ebay error they should fix... logical step was to reassign case correctly. Asked for escalation to supervisor. Explained scenario to supervisor who chatted briefly and asked for time to review and investigate. All sorted 15 mins later. Case closed - without any refund to buyer.

And a message in the chat with buyer that his account has been suspended or terminated and to use caution before taking any further action.