How do you mean, collect?

Wouldn't she have to post them back?

Personally I would be asking her to double check and make sure as you recall they were indeed the correct ones.

You could even send photos of both pairs and ask her to compare.

A zipper on the side is a pretty big difference. If the photo she sent isn't clear I would be asking for a close up of the side and telling her this is how she could tell if she got the right pair, that zip placement.

Oh and I do feel for you, I know what it is like, we had a similar buyer who arked up & wanted a discount on international postage costs and then complained later with a blurry photo of nothing. They just seem to have a feeling of entitlement, that they deserve money back.