Vinted complaint: refund

Hi For 3 days and half I’m trying to explain about a situation with a lady who’s scamming me and not paying for her item she’s recieved, but I’m not getting no where. I sold 4 bottles off cream to a lady on the 16th Nov, she never recieved which I could see at the time with recorded delivery online the parcel wasent recieved by her, so she got a full refund. But on the 10th Dec the item was delivered, I saw this with online royal mail tracking. So the buyer won’t return the item or pay me, so I’ve lost out in money. I’m trying to explain this with vinted customer service, but it’s useless, there not understanding I’ve sold this lady 2 lots of this cream, the 2nd lot she recieved and I got paid, but it’s the ist lot I haven’t been paid for as she was refunded. So I’d like to know who’s paying me for this item she’s got of mine !! The buyer is Haniipee.

Thankyou

Mia Dinnes