Unfair sales practice from AfriWheels Montana Pretoria

My son bought a secondhand car from AfriWheels in Montana Pretoria the 22nd of Nov 2025, the car gave problems within 10 days from receiving and went into limp mode from overheating, the the car was taken back to them for repair where the salesman Mike and his manager Kevin Coetzer told him that the radiator was blocked and the head gasket has blown from overheating and that it was because of his own negligence, they took the car to the premisses of CV Masters in Pretoria for an inspection report where it is now standing unattended for almost 3 months, we send them a letter of demand to refund us for the total amount paid, but they refuse to communicate with us, after contacting the Zambezi test centre we find out that the current km,s on speedometer also differs with about 100 000 km,s from the recorded km,s on the ENATIS system, and a ***** case has been laid at Sinoville saps detectives