Breach of trust by buyer

Hi experts, I entered into an agreement of sale for my property with a person. He paid me some amount as earnest money and made an entry on the agreement for the same. He asked for 4 Months' time for full payment/registry and we agreed. After time collapsed on the sale agreement he started harassing me and breach the agreement. A) On meeting, we also decided that buyer will arrange all the NOCs which are required to execute the sale deed. I don't have this in writing but I have voice recordings of our meeting in which he's saying that he will arrange the NOCs. B) He never paid the entire earnest money ( I dont have this amount written in agreement but I have whatsapp chats with the person regarding the same ) C) Recently, I recieved some unknown RTGS in my account after 2 months of the expiration of sale agreement. This person is calling me and saying that the person with whom I entered into the agreement sold this property to him and now he will go ahead with the deal. I don't know this person and never met him neither signed any agreement with him. This person keeps calling me and harassing me. On the other hand he is forcing me to sell my property to him. I told this person to reverse the RTGS transaction as I never signed any agreement with him. D) I noticed in my agreement that there is a clause saying that "buyer can get transferred this property to anyone or his name and make any profit out of it" I don't want to deal with these fraudsters because it's been more than 7 months since I signed the agreement and the same has expired for more than 2 months. Also, It feels like these persons will cheat me again. I am ready to return all the money I received from both the persons. Please suggest something usefull Thank you