Vinted complaint: Courier Stole Parcel

Went to ship out a parcel and the courier was organising parcels already in the inPost locker. He said to me and another person, he will be 30mins so he will take the parcel and sort it out for us. I trusted him (when I shouldn’t have) so me and the other person gave him our parcel.
I saw him scan others and stick labels on them so I don’t think my issue would have occurred.
After 2 days, I checked the tracking and my emails. Tracking said “ seller created label “ so I reached out to Vinted multiple times explaining the situation repeatedly and I kept receiving the reply of “ we need the ation email to investigate “ when the issue obviously is, the parcel wasn’t scanned.
I reached out to Inpost aswell, they said talk to vinted and they can’t help.
I gave the location, date and time. It’s been very unfortunate for the buyer as they really wanted the parcel and I feel so bad. But the incompetence from Vinted and Inpost is insane.
Very frustrating tbh.
Vinted could probably access the footage of me handing the parcel to the courier as proof of me sending it out and that im not making it up. Maybe im the idiot in this ? But I should be able to get help in this situation.