Transmission Noise problems of the 2012 Chevrolet Silverado 1500

I fought gm on this for 7 months. And did so 30 days from my purchase date. When I slow down my truck makes a horrible clunking noise. And will rev up in a sense and push you forward. Most of the time it's only probably a food but other times I has caused me to go through stop signs. Luckily no one is there but I fear that when I have my fiance and 3 kids in the truck I may get pushed forward and t boned. Or I may go into someone in front of me. Or into a fence. And they say it's normal every time. But it's getting worse and my thing is is if it's normal. . Then it's a serious issue. I have read reviews about other people having the same issue. This should be recalled. It's not safe and definitely not practical. They say it has something to do with my 6 speed. But I fought gm and he place I bought it from for months and months. Starting from repairs on my truck that was promised to be fixed to this transmission issue and them claiming they fixed it with some sensor. Then lying saying they never fixed anything when gm questioned them. Luckily I had someone that worked there that felt bad for me so he gave me all the info I needed. All in all gm ended up giving me a bumper to bumper gm warranty for 4yrs. For a problem they claim was normal. That's generous of them. But it's getting worse and I'm scared for my families safety.