If so, can I do something?

Evening her loved ones… … I have a concern or an important question on the topic of car sales & fraud. My friend and I sold our Smart ForFour via an online vehicle market to an older gentleman for 3,200,00€. He contacted us and told us he needed the car for his sick wife. Since the car had problems from the beginning with the throttle flap and we drove around with the error for a while, we had decided the car before the sale still r We didn’t want to sell a broken car. So we paid 300€ in cash for the first repair… but the error was still not fixed. Vehicle back into the workshop and that should be another 300€ amount… but on account! Had a folder with all the bills we got from the smart center, except for the last invoice from the repair of the throttle flap, 300€. It arrived only when the gentleman already took the car with him. had. Had agreed that we sent him the last invoice via post because of the guarantee of the throttle flap. Today I looked on the Internet and see there… Our smart… and that for proud 5,600.00€. But what was with his sick wife for whom he wanted the car? And why did we then make the trouble to get the car repaired, although the guy apparently knew from the beginning that he would sell the car again? Arbitrary deception? Since we were still in Besi I wanted to know if we can at least try to get him to take over the last bill? That’s still open. Human, I’m so angry. Did we get our spared out so that we don’t sell broken cars and now something like that… We could have bought our two children something nice of that too =( You have to do something… or? I hope everything is so much understandable. I’m just so upset…