Renault PMB - Defective Vehicle Sold

Bought a 2nd hand Renault Duster from them with the assurance of no rust and a 101 point check done. After purchase discovered a large hole in the floor from rust and large amounts of rust under the windscreen. Renault "fixed" the rust but refused to put us back into the vehicle, forcing us to buy a replacement, which we had to do elsewhere as they had nothing suitable and were attempting to overcharge us on what they had on their floor (ie bought in from another dealer to be our replacement and then wanted R20 000 extra) Renault now refuse to pay the additional on the road costs and bank initiation fee charged on our new purchase