A5 issue with a buyer

Hey everyone. My dad sold his Audi a5 S-line, had forged built motor and every issue afterwards sorted. Had a guy buy it and after 4 hours comes back and the car sounds like sh*t. The issues (what I saw) gearbox issue, hand brake issue, traction control off (couldn’t turn it on). All issues he didn’t have for 5 years.

He said he was going 150km/h etc. I reckon he had it faster. I think he’s flogged the car and now coming back.

My dad loves the car but pulled the pin in buying an s5 v6 supercharged and that’s the reason for the sale.