Advice for when InPost goes wrong.

I've never had an issue before so looking for some advice. I sent an order using InPost lockers and the buyer has reported that the wrong item arrived. They received a pair of shoes instead of what they bought from me, looking at the pictures the buyer uploaded InPost has put the label for the item I sold on the wrong parcel. I spoke with the buyer and I do believe that they're just as shocked as I am about it.

I've escalated the issue to vinted, but it didn't give me the option to upload proof or anything, will they ask me for this later?

I've made a slight error in that didn't take a picture of the packaging before I posted, but I do have time stamped video footage from my ring camera leaving my house with the package, there's only 10mins between me leaving the house and the parcel being posted.

Has this ever happened to anyone? How did it end up getting sorted?