Seller asking for a return due to misleading ad and not picking up the package

Hello,

I need your opinion following this situation: I bought a pair of pants that, according to the terms of the listing, were supposed to be new and size 40.

Upon receipt, I noticed that there was a used handkerchief in one of the pockets, that the color was faded, and that the label stated it was a size 42, which is too big for me. I opened a dispute, and the seller asked for a return at my expense, which I felt obliged to accept even though it didn’t seem right to me.

I am notified that the package has arrived at the drop-off point. After 10 days, Vinted tells me that the seller has collected her package and that I will be refunded within the next 3 days. Indeed, I am refunded for my purchase minus the return shipping costs, but today I receive a message from Mondial Relay informing me that I have a package that has arrived, which doesn’t surprise me since I had ongoing orders. And to my great surprise, what do I find in the package??? The very pants that the seller apparently did not collect.

So my question is: what do I do with these pants?