Door Hinge problems of the 2001 Chrysler Town & Country

The driver's side rear automatic sliding door ceased working during cold weather conditions at random times over a couple of years & then suddenly the automatic function of the door would not work at all when the button is pressed from the inside. Even worse is that the door will not open when using the manual handle with the lever. This is extremely dangerous, as small children could be trapped. Earlier when I took it to a dealership, they stated that a new track harness & something else was needed at a cost over $500. We cannot afford this. Doors should work manually without $500 parts. There is nothing physically wrong with the door, nor has it been in a collision etc.