Radio/tape Cd Player problems of the 2007 GMC Envoy

I was stopped at a traffic light , I was listening to my radio . The light changed I put my foot on the gas pedal and truck didn't move. . It was then I realized the it stalled. I put in neutral and started it back up. And continued to work. After this initial time it was happening two to three a day , atleast three times a week for months. . I took it back to dealer 15 times . I have a paper trail for this. They told me they could not find anything wrong with it. I have had my vehicle for going three years and have only put 11,000 miles becauseii am afraid to drive it any long distance . I don't want to break down and be stuck alone. I have already put a complaint into gm about this and they have done nothing . It is total bull. All I want is my car fix so I can enjoy it. I am paying for a car that just sits 80% if the time. Look st on star if you don't believe me. Please help me get my car fix right.