Do my son sold his car about 2 months ago for about 500 quid . The bloke who brought it has just rocked up on my doorstep asking for money to help tax it . Apparently it’s more expensive than he thought. I was calm and told him to go away or I’ll call the police . He accused me of fighting my son’s battles which made me angry as my son can fight them himself . It was more the thing that he’s come to my house and has also been texting my son chasing him for money . I recently changed my car and the tax was dearer should I ho back to the car dealer and demand money back ?