Second Hand Car Dealer Fraud in kolkata

I have bought a car Huyndai Verna 2011 model car from second hand car dealer in Kolkata on 19/09/21. At the time of dealing I found that the road tax of this vehicle will expire on 31/09/21. So I asked them is it possible to pay tax in my state that is in Tripura instead of paying tax for west Bengal because I am from Tripura. Then they ensured me that they will give me N.O.C for my state and will be able to pay tax in my state and there will be no issue. For that they charged me rs 10000/ and ensured me that they will do the work within a week and send me all documents by courier. After that I bought the car and did all required necessity they have asked to do and paid as per dealing. Now its been over 3 month and they did nothing, not N.O.C nor giving my car’s originals. When I call them they are not responding. I have full vedio footage of that complete dealing. Please suggest what should I do?