Online Fund transfer to buy Iphone (Ads in OLX Bangalore)

Dear Sir, I was in search to get used iPhone 7 in OLX, i got some contact person name: Vignesh i texted him through OLX chat and he replied with his whatsapp contact no. [deleted]. i contacted his through whatsapp and had a conversation regarding, a) Why you selling iphone for lower costs, is this are 2nd copy mobiles? His reply: No, these mobiles are ORIGINAL and it's Harbour tax free goods so you are getting at lower costs. b) i will order a mobile, book it now and when can i get it? His reply: Sir, for this you need to make a 10% advance payment of cost of the moble. then i made a payment of Rs. 3000/- till i make a payment he use to follow-up frequently. once it has been credited to his account, if myself call to his no. he never picked-up and no texts also. later on i got a text from him saying that, sir our billing procedure got changed you have to another 10% of advance and all. Till now am interacting with him to refund my amount but he is not agreeing for that and telling make additional advance payment of 10% and you will get mobile delivery. Dear Friends, please don get cheated with these kind of persons and please help me out to get my amount back. Still he is texting me to make further payment but we never refund.. so that we can track him and i do have his active account no. details too. please help me what i can do further? Regards, Vinay