Owners/service Manual problems of the 2005 Chevrolet Uplander

While driving down the road at 40 mph in my chevy 2005 Uplander van the passenger rear door opens and a continuous alarm sounds. (this door was next to my 22 month-old). Previously the door would open while in park. The door has been found open in parking lots in town and in our garage. Our door on several occasions has attempted to shut, but would not, then it alarms and opens back up. We have tried to manually shut the door but it would not shut either. The door also tries to shut with people in the way. My daughter went back to the van to get a toy and got her toy while I was blocking the door. The door pushed hard against me trying to close, it almost shut me in the door. The door would not reopen like it is supposed to with something being in the way. If that had been my daughter it would have shut her in the door, probably killing her. The van has been at a dealer atleast three times. Each time the problem was not fixed. The problem was blamed on dirt on the contact, so the contact was cleaned. The next time the computer was blamed. This last time a switch is being replaced. I am terrified to let my kids ride in this van because I fear for their safety. Please help.