Vehicle Shudder problems of the 2011 Dodge Grand Caravan

Vehicle rolls forward without stopping when in reverse & the brake is released & on a shallow incline, without accelerating (vehicle nose down slope). Two days after having my 2011 Grand Caravan, which I park in my driveway that has an angle of apprx. 15-20 degrees & the vehicle is parked nose down slope toward my home & garage. The first indication of a problem was on entering the driveway and shifting into "park", the vehicle rolled forward 6"-8" inches. This issue started 2 days after having the vehicle. Prior to the vehicle rolling forward all vehicle operations seemed normal, there was hardly any roll at all (1"-3" in. ) when "park" was engaged. The next clue of a problem was that the vehicle would shudder when accelerating in "reverse" & at low speed. This problem does not happen every time the vehicle is reversing, but has become more frequent. While driving noise has been detected from somewhere beneath the vehicle, but is not heard frequently, only 2-3 times. The worst issue present is when the selector is placed in "reverse" and I remove my foot from the brake, without accelerating, the vehicle continually rolls forward without stopping. If the vehicle is in "reverse" and being accelerated up the incline and I remove my foot from the accelerator the vehicle will roll forward down slope without stopping. The closest comparrison is that it feels like driving a vehicle with a manual/standard transmission. It seems that the transmission issues is getting worse and I've only had the vehicle since 14 October 2011 and for 772 miles. These issues have been brought to the attention of the dealership & their service dept. & to the Chrysler, Dodge, Jeep case management dept. I have continually been lied to by both departments and calls to case mgtmt. Ignored/not returned. My family & I feel very unsafe in this vehicle & have lost all trust in Dodge.