Transfer Case problems of the 2006 Chevrolet Suburban

Would drive fine at times. When restarted, engine would lose power, very sluggish, unable to pick up speed. On dash, message would read 'service stability'. Took to our local Chevrolet dealer, they were unable to repair, they could not tell me why message would appear, absolutely clueless to the problem. Then took my vehicle to my local mechanic, he stated he had four other GMC vehicles come in with the same message on dash. He stated it has something to do with the transfer case. That's more than what the dealer said. My mechanic stated he attempted to get the part, but item is on back order from manufacturer. Does this indicate that many many more vehicles are experiencing the same problem? have been experiencing this problem for a while. My vehicle only has 60,000 miles, way under the amount of miles for a vehicle 6 years old. This has to be a defect. Please help!!!!!.

Driving in a 55mph zone, vehicle transmission failed. It appeared that the auto 4x4 switch was changing. Placed vehicle back in 2 wheel drive, driving 55mph, transmission failed again. When switch was set in auto 4x4, the vehicle ran in 4 wheel drive but no other settings worked properly. I have had multiple diagnosis attempts. There are bulletins on the auto 4x4 actuator and on a transfer case motor sensor.