Inpost locker has stolen my parcel and Vinted won’t help (no personal info)

Hi

I posted a batch of around 5 Vinted parcels over a week ago. 4 of them went and were received without a hitch but the 5th one has disappeared.
The day after I posted it, I got a message from Vinted asking me to send it. I contacted the buyer and advised it had been sent but hadn’t updated for some reason. She replied saying it happened to her occasionally too and not to worry as it would turn up.
It didn’t turn up and Vinted have refunded her for the order and given me a 1 star as I ’didn’t send the parcel’.

I‘ve contacted Vinted CS and they have said there’s nothing they can do as I can’t prove I sent the parcel. I asked them to file a claim with InPost as I provided the exact time and day I posted it - so surely they could check their CCTV. Vinted will not do this, nor will they respond to my request for their complaints procedure.So, I’m down the item and also got an unfair 1 star review.

What are my options - if any?

Many thanks for any help/advice anyone can provide. I would much appreciate it.