Got scammed on Vinted? how can that be?

I bought, what I thought was a bargain pair of Adidas Samba trainers, in black for £35 on Vinted. I received yesterday, only to find that they are dupes.. They are cheap and nasty, and they feel all wrong. I checked with a local store, only to find that they are indeed copies... the sole is made of hard plastic, not rubber, the "Samba" logo is printed, and not embossed, the stitching is poor, the material is plastic and the label inside the tongue, is a copy. This was clearly a counterfeit pair of Adidas trainers. I wrote to back to the seller and his reply was: " I will offer a refund, you will be given an amount of time to send the shoes back. I want to make it clear that these or any shoes I list on Vinted have never been advertised as real shoes after all, would you really think I'd be selling real ones for free? Please consider next time as I would have told you." Once again I never advertised them as real ( he did..) and you bought them without any guarantee that they were real ( I did) because they were advertised as it ( they were not ) here's the listing... https://www.vinted.co.uk/items/6724273774-adidas-samba-og

So... Vinted are not moving, I can return the items, but I have to pay for the postage, returning a cheap pair of knock off's Surely something's not right here, that Vinted can allow sellers to sell crap, and get away with it? I have photo's of the shoes, and they bear nothing to the real ones....

How can I progress further to Vinted???