2007 Mercedes ML350 new power steering rack

Sorry - Here it is. I own a Mercedes ML 350 2007 with 60k miles. The Power Steering Rack Now Needs To Be Replaced For Aprox $4,000. Car just had Engine (timing gear) Cam shaft replaced due to faulty parts for over 5k. Is it Normal to have to replace a power steering rack in a Mercedes with only 60k miles or could this be another "faulty part" problem? (I've read on line other people having similar problems.) The dealer will not help me at all, stating they already gave me a discount on the engine issue so I"m on my own here. I am also very concerned the transmission will fail next, (rough downshifting when driving slow. This is also another issue I've read about with the ml 350 2007.)Should I trade in this car before something else very expensive breaks? Any info would be very much appreciated since I don't have any $ left. Thank you. Lisa