How to file complaint against a person cheated on money for selling a scooter to me?

I saw the post in OLX and the reached the person for a used scooter. He said he is a army person. He wants to sell the scooter at 21000 after negotiation the price was 18000. When we confirmed the deal, he said he will start the procedure of changing the name in RC book, for that procedure he took 4600 rupees in three terms. After that he said the registration is completed and the scooter will be delivered to you by army base delivery. After the delivery started they asked for 8650 rupees as advance payment otherwise they won't deliver the scooter. Then the asked for a security deposit of 6500 rupees otherwise they won't deliver the scooter and it will go back to airport. Then they said your insurance is not completed, for that you have to pay 7500 rupees otherwise you won't get the scooter after these all transactions they said it is 10pm we will deliver the scooter on morning. In morning again they asked for 6500 as security deposit to deliver the scooter because the delivery is delayed for a day otherwise they won't deliver the scooter. This time I didn't paid the money. He said this is army delivery process, if you don't do the payment they won't get the mail and the scooter will not deliver to you. I have the few messages with him sharing the bike and registration card photos to me and I have bank transactions. In the bank transactions the name of the recipient is different when I asked about that he said that is office account. Kindly tell how can I file a complaint against this? Please advise me to get back my money. He said 18000 for the scooter and he took around 30000 from me