Draw an indictment in Thai

I need law assistance to draw an indictment in Thai language. I have bought a used car from a Thai, and sign a contract in Thai after all payment. In fact, I totally know nothing about Thai language. I found the car’s engine leaked oil terrible. Then I drive the car to the KIA service center, and they told that the engine needs to be open to repair. Therefore, I refuse to transfer the ownership with the car owner, and ask him for return the car. The owner refused, and pay nothing to me. I decide to sue for return, and have uploaded the agreement.