Yesterday (March 18), I traded in my car for a used Qashqai at a Nissan dealer. Car is registered 11 months ago with 3700 miles. Serviced by the Nissan dealer on 24 Feb 2020. I drove it towards home for 25 miles, low oil indicator came on followed by 'stop the car' signal. Dealer attended, no oil showed on the dipstick and after filling with oil they returned it to the dealer. Examination by the engineer showed, photos and explanation, that the oil filter used in the service was defective. I have taken the car home, but I want to return the car despite an offer of an extended warranty. This is because Nissan will not be interested and the warranty will not cover the possible damage in a used vehicle. What is the best process in returning the car?