Olx Seller - Seller sent me fake mobile phone

I ordered through cash on delivery a Samsung galaxy s** plus through an olx seller name OLX USER his phone number is ********** but he sent me a fake galaxy s* plus and charged me ***** rs after receiving the package i told him that its a fake phone so he said ok he will return and after some time he told that he has initiated a return but the courier person did not come even after * days his phone number is ********** he keeps telling me that parcel will be picked up by tomorrow but I think it's their set up only to make fool of the people. Now the seller is not picking up my phone and refused to send the address of his shop. Initially before buying he told me his shop address which is (** A, Bhatia Chowk, Kamla Nagar Delhi ****** opposite state bank of India) I told him that I will send the parcel by myself to this address but he told me that do not send to this address. Now I am living in Tamilnadu and he is from Delhi so I can not go there please do contact those persons so that they refund my money send a legal notice against them. I am attaching my WhatsApp chat with him.