Unfair treatment

I purchased a car at we buy cars at the Durban branch. The car started overheating 15km into the freeway from the dealership. I called in immediately telling them to send a tow truck to fetch the car and they told me it late and they would fetch it from my house the next day. Which meant that I had to drive all the way to my house making stops along the way because the car that I only Just bought that day was already giving me problems. The next day they fetched the car for testing. the car has been in they possession for over a month and i have asked them for a replacement or a refund and they have refused. they have insisted that they fix the car and send back to me. Jaco Venter the deputy manager won't even let me talk to his superior. I feel cheated because I'm paying for a car that i am not even using. They are not honoring the terms of sale which state that should I return the car there will be options to Repair, Replace or Refund. Which in my case they choosing to repair the car and i didn't choose that.