TWICE in the past month +. On [XXX] my wife and I were on our way to a family wedding and I was driving approx 75 MPH on [XXX]. I don’t recall if I had cruise control on or not as I rarely use it. There was no vehicle was in front of me for hundreds of yards yet all of a sudden the vehicle started to brake very hard. I accelerated as I did not know what was going on and I had a car in back of me that started to gain. THEN last Friday ([XXX}) with my wife following me in her car on [XXX] through Ellicott City MD I was traveling at approx 25-30 MPH through a very small historic town when all of a sudden the same [XXX] thing happened. DEF no CC on . When we got to our destination I asked my wife if she saw my brakes come on suddenly?. She replied yes and said she saw the truck dip hard. I told her the brakes did it again. She said I should call the dealer. I did not as they are USELESS! THEN the electronics. On Star has a catalog of my complaints. The radio selections I make just disappear from the screen: Apple Car Play disappears from the touch screen and just goes dark. I have to stop the truck..(per on-star) open the door.. get out.. lock it.. wait 2 minutes.. get back in .. restart the truck, and this re-sets the computers(s). RIDICULOUS! I do not have Sirius but the radio goes dark often for about 2-3 seconds., then comes back on. I was told it is my I-Phone is causing this. [XXX]! What does my phone have to do with AM/FM radio?? I was told by GMC there is a patch to update the software. Koons GMC told me there was no such patch nor recall. I paid nearly $80,000 for this piece of [XXX]! INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)