I just sold a pair of shoes to a buyer.

They were listed as used.

I listed that they were worn only 2-3 times which is the truth.

I did give them a clean prior to mailing as one would.

I packaged them up and mailed them off last week.

The buyer has now messged me that the shoes are broken and want a refund.

She has said the buckles are broken.
Im bewildered beacuse I noticed no such thing. They were fine when i shipped them.

What do i do now?