Buyer Filed Does Not Meet Description Case - How to Handle?

Want to preface this by saying that I have my returns turned off.

Sold a size L pair of pants. Buyer gets pants and messages me saying that pants aren’t XL and he wants a refund. I point out that he didn’t read the listing, then he asks for a discount if I can send the size XL. Tell him I don’t have size XL.

Next day, buyer files a does not meet description case with a picture of the floor of his car. I called eBay support and they basically said I’m fucked and have to provide a return shipping label.

How is this possible given that: 1. The item I provided was correct 2. They have the chat history where the buyer admitted to buying the wrong size 3. I have my returns off 4. Buyer’s photo was the picture of the floor of his car

I assume I’m just screwed here because eBay fucks over sellers buy anything I can do here?