Hi, i am very depressed, i have sold a car in melbourne, run perfectly, no issues were found by mechanic. Buyer was interested to buy, he inspected it clearly, check with driving, he found no issues at buying time. He asked for RWC, even RWC was provided with car, mechanic smoothly clearly RWC, and found no issue. Now after 3 days buyer wants to sue me that car has engine fault. He want money back, and need to sue me. Even i dont know what happened with car after he bought, at time of buying everything was clearly checked, he was satisfied now he pressurize me. what should i do?