faulty eBay item returned and seller has raised a case??

[Gavino]

i bought a flooring tool from eBay. it became defective very quickly, then stopped working. i returned it with the post office using a qr code, and it shows as delivered. now, the seller has raised a case saying they have not received the item. unbelievable. Is there anything i can do should they find in their favour?

[Pezza54]

Did you send the parcel Royal Mail Tracked 48?
If you did you should receive a photo when it is delivered

I have read that tracked 48 is the same price as standard 2nd class and business users prefer tracked 48
That explains why the postman is now frequently taking photos when I answer the door. I thought he just fancied me