Transmission Stuck In Gear problems of the 2012 Chevrolet Traverse

This incident occurred twice. Driving down the freeway at freeway speeds, a loud clunk was heard, the vehicle jerked, check engine light appeared, check stabilitrax and traction control messages appeared and stabilitrax disabled, speedometer remained frozen at speed this incident occurred. While driving to safe location to stop, vehicle appeared to be stuck in a specific gear that is lower than normal for freeway driving, rpms were much higher than normal. When attempting to accelerate from a standstill, vehicle appears to have no power (probably due to accelerating from 0 mph in a higher gear). I took vehicle to bowman Chevrolet service center for attention and they were unable to duplicate the incident though they did state that they see error codes in the system for loss of communication. After testing and troubleshooting for up to 2 weeks, service department stated that they are unable to determine the cause of the error but during their testing they found the battery needs to be replaced. Assistant manager of the service center states that a battery replacement may or may not fix the problem. I made a case (#8-3668973225) with Chevrolet but the adviser received information from the dealership that was false and stated there was nothing further he could do. The information he received from the dealer is that they were waiting for me to authorize charges for additional diagnosis while the assistant manager reaffirmed to me that there is no further diagnosis that can be done on this vehicle. I did authorize bowman Chevrolet to replace the battery. My concern is that I am now taking back a car that is a safety hazard and allowing my wife to drive, and daughter to ride in, this vehicle that has a known issue. Luckily for us the issue occurred at night when there was no one on the roads but if it occurred during rush hour it could cause an accident.