Sold car and did not disclose any off the Problems

How unfortunate can life be... we bought a second hand Merc ML500 from this dealer. The dealer did not disclose to us that the engine was replaced - with a ***** second hand one. We had the car one day and it broke down! We had to fight to get it fixed. BUT the car broke down every week - costing us a fortune - we had to pay. We would call them and they are never available to take our calls. We took the car for a 150 point check and found oil in the cooling system. Yip - head gasket blown... Rear brakes worn and needs urgent replacement. Spark plugs so burnt - needs urgent replacement. We were told the car was serviced before we took ownership - no way! Beware of these people - they look honest, but don't trust them. We have a bill of at least R 50 000 waiting on repairs. They were quite keen to trade my immaculate Merc with full service history at MAX trade in - now I know why - so they could dump the s**** metal on us. If they had any conscience they would call us and offer to pay at least half of all the repairs! The chances of that... ?