Front Suspension Wheel Bearing problems of the 2007 Nissan Murano

2007 Nissan Murano awd w/ 84k miles. Took vehicle into Nissan dealer service dept. In July for noises in engine area. Diagnosed as bad wheel bearings on 1 side of vehicle cost $600. 00. Returned to dealer approx. 1 month later, again hearing noises coming from engine area. Was again diagnosed w/bad wheel bearings on other side & was told replacement from 1 month prior was defective & needed replacement again. Questioned dealer service dept. Diagnosis, indicating that I also smelled either oil burning or some kind of fluid burning when driving. Without further examination of vehicle, service dept. Recommended a fluid flush, I indicated that the fluids had just been flushed 1 month prior, was told no other problems were indicated when vehicle was inspected earlier that day. Smell of oil or fluid was dismissed by service dept. Received a call later that day from service dept. Indicating repairs to defective wheel bearing & second wheel bearing completed, car ready for pick up $400 bill. Picked up vehicle @ approx. 5:30 pm. As I drove home there was a good amount of traffic & vehicle speed did not exceed 30 mph for majority of trip. Upon clearing of traffic & further acceleration to approx. 45 mph, there was an extremely loud bang that came from what sounded like the engine area of my vehicle, accompanied by a dragging & grinding sound coming from the bottom of my vehicle bringing my vehicle to a quick stop. It sounded like the bottom of my vehicle fell off. I managed to pull vehicle over to safety & next day had vehicle towed back to dealer. I was then informed by dealer that the transfer case on my vehicle had broken, that the vehicle was beyond the warranty & the repair cost is $3,400. This may be a problem in the awd model. There are many similar incidents posted on the internet. This part is defective & needs investigation, had I been on a highway when this happened the outcome could have been catastrophic, please help! don't wait until a true tragedy occurs.