8 Speed Transmission

I was just wondering if any other shop is having problems out of the 8 speed transmission in the new trucks. We have put 2 new transmission in a 2016 gmc and it is still having the same problem. The truck is revving up with out touching the gas and after putting it into gear it finally stops. First we had to order all of the parts for the bulletin but then gm told us to put a new transmission in it. I am just wondering if its our techs or if it really the transmission gm is giving us.