Indian Army — indian army officer has cheated me for 11000

Address:	Chennai, Tamil Nadu, 600010
Website:	Olx

In olx I saw ad about the Samsung s9 plus and the seller happened to be Bsf army officer
He agreed to sell the mobile for 22000, so before receiving the mobile he asked me to pay half the amount which is 11000 and I did transfer the amount via paytm
Payment was first 4000 and then 7000 after the courier receipt he sent
When it reached chennai the courier Boy called up and asked for another 6000 for the parcel to deliver it and I said I won't pay him any money, so the courier Boy refused to deliver the mobile and I did tell him that as soon as I receive the mobile the just second payment will be done still he refused and now the seller isn't answering the call or replying to texts
Name of officer - satish Kumar bsf officer
Courier Boy name - manjeet
Mobile number of satish - [protected]
Courier boy's number - [protected]