Accident damaged demo vehicle

Guys I recently purchased a demo vehicle on the 27th November 2015 from a Mccarthy preowned menlyn,I saw damage on the car before I took delivery,they said they'll fix it,came Wednesday 02nd December 2015 to collect the car from me at work,to get repaired,I got the car back today,looking worse than it did when I sent it back.the over spray it has on,I am not happy,I want to cancel this entire transaction,or they BETTER GIVE ME the same vehicle but accident free.i am super cheesed off and fed up now.this is not on and not fair towards me as the consumer,I can't pay R250k for a demo vehicle but it's already got accident damage,and it's already been to panel beaters,when it's not even my doing. Get me another damn vehicle the exact same one or else we will just sort this out in court.this is shocking service and I don't want this car.its going to carry on niggling me that it was in an accident.the entire car is full of egg shell,they need to exchange this vehicle in this coming week.or we will sort it out in court.but I am not going to pay R250k for a 2015 opel corsa 1.0t cosmo Ecoflex and it's accident damaged and they just shut up about it!!!!! Totally fed up.