I know I'm late to this thread... but recently had some of the same experience with my daughter's 2008 VUE. I'm hoping this could help someone in the future.
Engine code P0700 would appear and transmission would not move out of 1st gear unless reset the engine code (OBDII) or sometimes letting the car sit over night.
GM Dealer wanted $5800 for a transmission replacement. My local mechanic stated his transmission service would not touch the Saturns.
Finally found a Transmission specialist about 20 miles away. This place only does transmissions and has over 30 bays for service. They replace the Techum for $1065. They state they do about 8 of these GM trans per week. Car now shifts fine.
Agree... Runaway for the GM dealers !!!