Issues with vinted item on delivery

I bought a “brand new” Manscaped Essentials Kit from a seller with lots of positive reviews. When the parcel arrived, I opened the box (annoyingly I didn’t think to record myself opening it), and the main trimmer simply wasn’t inside. The box only contained the charger, attachments, brush and cream.

Looking back at the packaging, I can’t tell whether it had been opened and resealed previously. Part of it looked as though it may have been opened, but another part of the seal still appeared intact. I genuinely can’t say either way.
Rather than accusing the seller of anything, my first questions were simply whether they were aware the trimmer wasn’t in the box and whether there may have been another box sent, as I thought there could be an innocent explanation.

Instead, the Seller’s response immediately focused on how buyers could remove items and falsely report them as missing, and said they were “very disappointed”. That struck me as quite defensive given I hadn’t accused them of lying or acting dishonestly.

For context, this is the first time I’ve ever reported an issue with an item on Vinted despite buying quite a lot through the platform.

The seller has also mentioned that Vinted can check the parcel weight, but I’m not entirely sure how that works because, as far as I was aware, Vinted shipping is selected by parcel size rather than weight.
Has anyone had a similar experience, or knows how Vinted usually deals with cases where the main item is missing from the box?