Ali Express Scam. Help!

I purchased a wig from a vendor called Kevin liu (Fashion Pretty Hair), the wig came to London about 7 days later but it wasn't what I asked for at all. I was very unhappy with the wig so I sent it back. Before I sent it back I contacted Kevin and I told him that I was very unhappy, he was nice and told me to return it and that they would give me a full refund including the postage cost. I sent the item back over a month ago and constantly contacted Kevin to find out if he had received the item. He claimed to have just received it a few days ago (Monday) and now the he doesn't want to give me unless I give him a good feedback. So I did left a good feedback even though I am very unhappy with his service. now he is no longer responding to my messages. I have sent him several messages but he is not responding. However before this, he would respond to my messages instantly.

All I want is my money back $300. Unfortunately I didn’t open up a dispute on ali express because he seem so nice and willing to help and now that I tried to complain to ali express through their customer support chat system (which by the way is the only way to contact to them) they keep saying is that the protection time is over, that there is nothing much that they can do. This is really not fair because I can’t afford to loose $300 just like that. I can’t believe that ali express has no other means of helping me retrieve my money from a very bad vendor. I am sure that i am still entitled to my money as agreed, because it was the exact day that the goods were delivered to me that i sent kevin an email stating that I was very unhappy with the item and he told be to send it back and that i would get a full refund.

I told ali express customer support to access my messages to see the conversation between me and him but instead they asked me to send screenshot photos of my messages which I did. But every time I asked the person I was chatting if it was possible t make kevin pay me my money, the reply was most likely not.

Can any one help me apparently they have no contact number so I cant even speak to any one to explain my situation