Lies and selling car to pensioner unwillingly

On 29 April 2015 we went to GM to look at what cars they selling and their prices. We met Simon & Karabo who both showed my mom a two cars (Mokka & Captiva). We test drove the Captiva and my mom told both guys that the car is big and should be heavy on fuel. Simon rep**** by saying the car is a fuel saver because its aerodynamically design. <br> <br> On the 30 April 2015, Karabo called and mom again told Karabo that she doesn't want the car. They repeatedly called with Simon telling my how good the car is on fuel. Then Karabo came to my house at 11h25 and we sat half day there till we got car at 18h20. Apparently the car had 25l of fuel and we filled up to full for R560. We managed to get 400km when fuel warning was on. We took the car back on 4 may telling them we dont want the car anymore. Again Simon and Karabo told us they can't take it back because they got paid by the bank.<br> <br> Karabo took my mom to a white guy who told my mom that the car its a fuel saver because his chev utility gives him 14l/100km and he's dying of cancer, and the fuel will improve after 2000km on captiva. Mom signed a document that they take back 5% of deposit and now that doesn't apply and they dont the car back.