General Motors Corporation Truck started by itself without key Detroit Michigan

I came out of Walmart hit the remote to have the door unlock before getting to the car. When I got to the car the door was still lock and I heard a car running. I thought it was the car next to mine I hit the remote again to open the door and it still wouldn't unlock the doors and I saw smoke coming from under my hood and realized it was my car running. 

The car ran for 3- 4 minutes and then it cut itself off for about minute or more and the smoke was substantially's more at this time. A young who was passing by I asked if he could help me, I told him that my car is  running by itself and it is smoking. He lifted the hood and informed me that it was on fire, he saw another man asked if he would help and asked if he had a wrench.

They took the wrench and disconnected the battery. We thought the truck was going to blow-up the fear of people getting hurt created a sense of urgency. I contacted Corporate office pertaining to what happen and I was told that they would have someone to contact me in a week. An attorney contacted me and told me that it wasn't a recall and that the recall had expired.

The attorney informed me that he wasn't a GM employee he was contracted attorney and that he doesn't know anything else. He was agent Byran Schwartz. I spoke with a representative at NHTSA and he informed me that it was an electrical problem steming from lights didn't work. The problem happen before the expiration date from what NHTSA informed me.

I feel that General Motors should replace my truck due to problem. The insurance totaled the truck out and I am without a Ptransportation.  I was given a check that I can't find a truck for what I was given. The truck was never looked at and there is no reason why it happened other than it was electrical.

Please help