About buying a second hand car

I tried to leave a comment on one of your articles, and pressed ”submit” but I’m not sure if it worked, so please forgive that I send this messege here too.I’m Japanese and my husband is Portuguese living in jp. His mother in Portugal was trying to buy a second hand car. The seller mentioned the car had one flaw, and that she could have a test drive if she just paid deposit. She accepted the flaw and sent deposit to him, but the car hadn’t delivered to her. It was in the port and a staff there wrote a note about the car “this car has many many flaws”. Then the seller suddenly said ”the process had been cancelled, bye.” She asked for returning deposit, but he ignored. She had had another trouble with another seller before this seller. She lost her car before, and this happened again. In Portugal, are there so many bad troubles with second hand car sellers? She has been betrayed many times, and lost cars and a lot of money too. I don’t know how I can help her or whom I should ask for help, so I’m trying to ask here (I just found this article so…) Is there any third party about buying a car in Portugal, for instance? Or do you know where she should dispute?If I could have your reply, I really appriciate…