Hello, I sold my car to a guy and he inspected the car for 2 hours and he gave me advance money of 300 dollars and asked me not to sell the the car to the other party who wanted to buy my car the next morning. So, the next night the guy came and bought my car and checked everything and brought his friend with him. He asked me if I had face any problems before, and I told him that I did not face any problem with the car when I drove it or since I had it. I have the logbooks of the car, and did a minor servicing ( oil change and filter change) from a garage name the auto doc and gave him the receipt. We signed the papers and did every procedure and we shook hands and he left with the car. I have already given the disposal slip to RTA. Now after 2 days he is telling me that there might be a problem with the car and he wants to refund. I have already told the other buyers that the car is sold and now he is telling me this. He said either I have to refund or share the cost. He also mentioned that if he goes to the court he will win for sure because I told him I did not face any problems with the car. I have checked the rules and regulations, and it is written on the website of NSW Fair Trading that once the car is sold and is a private dealing, there should be no problem for the seller. That guy is calling me over and over again and as an international student this is hampering my studies. Should I be worried? What should I do? When I had the car I faced no problems and now he is telling me this. What if he did some crime with the car or he changed some parts from that car and now trying to take advantage? I am not obliged to anything right? Please tell me what I should do. Thanks a lot!