Buyer Has Request Return for Genuine Trainers That Have Been Confirmed as Authentic by eBay

[smartfella]

Hello everyone,

I recently sold a pair of Nike trainers for £150 that were confirmed as genuine by eBay's third-party trainer authentication specialists, and the buyer has since initiated a return — that eBay approved automatically, despite my listing showing that I do not accept refunds — on the grounds that they didn't recognise the label, even though the listing imagery was clear over several images. The shoes are 100% genuine, approved by experts, and came from Nike directly.

My questions are:

1. Do I have to accept this return?
2. How do I dispute this? 
3. What happens if/when the trainers return to me, via the third-party specilaists again, and they are damaged? 

Thanks in advance

1.