Vinted complaint: Buyer did not pay me and got away with it!

So I posted an item and the buyer messaged to say she didn’t receive it.
The tracking said delivery attempted but address inaccessible.
So vinted suspended the order and once I messaged vinted about the suspension they said they’d investigate into it, but once they said that they cancelled the suspension so the buyer received a refund.
So I called Royal Mail about it and they said the parcel is waiting at the buyers local delivery office and the buyer can collect it or request re delivery. so I messaged the buyer to say she can collect it or request a redelivery she refused and said it’s inconvenient for her to do so.
So a few days after they cancelled the suspension I checked the tracking and discovered that it had been re delivered. I messaged the buyer again to this and if so that she would need to pay me for it. She said she didn’t want to repurchase it. So I contacted vinted support again to explain the situation but they didn’t help me one bit! They said they cannot do anything about it as a non integrated shipping provider was used. And that’s all they had to say! Every time I contacted them further they just close the case on me!