Car overheating after two weeks. want to reverse this deal

Good day. my name is mashudu muthivhi. I recently purchased a vehicle from you guys which is a BMW 1 series 118i F20 5 door. The first week obtaining the car, the car started overheating and coolant was being consumed alot. i spent over 1000 rand that week dealing with coolant until i left it there at the dealership. lloyd the next week said they checked it and there was nothing wrong but i know something is wrong. There is a problem on the cooling system and head gasket. clearly you guys did not take the car to bmw dealership at all. its been two weeks and im dealing with alot. Honestly i am fed up with this car. i left it with lloyd at the dealership. i have no car to go do my work anymore because you guys gave me a car that overheats. Your guys' services to be honest are not great. I have communicated with insurance and they said there is a 30 days period and i have the right to request another because clearly you guys gave me a broken car. please sort this out immediately. i am sending this report to police and lawyers including ombudsman. i am really angry and i am not happy at all. please give me a another car please. it's my first time buying a car and already I am having this trauma. Two weeks already i am having a problem..