Indian Army — parcel of iphone 6s 128gb was not delivered.

I saw an ad (Ad link : https://www.olx.in/item/iphone-6s-128gb-six-months-old-ID1jMB7z.html) on 4 may. So i messaged him and he gave me his phone number ([protected]). We texted and i was satisfied with the phone we agreed the price on 15000 rupees. He told me he was out of station as he was an army personal so he will send the through courier. He sent me his aadhar card and army canteen card so i did not suspect that it would turn out to be a fraudsters. He told me to make an advance payment of half the price ie 7500 rupees then he will deliver the phone. So we sent each others id card and i paid him the said amount through the paytm number [protected]. After that he sent me the receipt of the courier and made me believe that the item was to be delivered to me. The next day ie on 7 may, i called him again as the phone was not delivered to me until the evening. Then again he told me that he will talk to the delivery boy and confirm with me. After some time he called me and told me that due to his military rules, for an item to be delivered we have to pay the full amount so we argued for a while. He kept telling me that i will lose the 7500 advance payment because of the rule so i had no choice but to pay the remaining amount ie 7500 rupees to another paytm number [protected] which he provided saying the previous paytm number had some issues. After i paid the total 15000 the phone still wont be delivered and i asked him the reason. Again he told me to pay an additional amount of[protected] for insurance and 2100 for delivery charge). So i got suspicious and requested him a whatsapp video call which he declined instantly. The real reason here is that the first time he told me that i should pay the advance of 7500 and on receiving the phone i will have to pay the remaining amount. This is what we agreed upon but on the contrary he asked me to pay full amount and still i paid him and he was asking for more which he never notified me earlier. He is still saying that if i dont pay him the 7100 for the insurance and delivery charge i wont get my money back. So please help me with whatever way you can and i will be very happy if you can get my money back.
The transaction id for the paytm payment for which i mentioned above are [protected] for rs 7400, [protected] for rs 100 and [protected] for rs 7500.