Carrier/rack problems of the 2017 Hyundai Sonata

On Saturday 9/16/17 I was at a stop light sitting still when my car stalled and went dead. I looked at the dashboard and saw the engine light was on. The brake was frozen and before I could restart the car it rolled into the vehicle in front of me. There no damage to her Jeep. However my car hit the spare tire and rack on the back of her trunk, causing damage to the hood of my car, the grill and lower bumper. We did not exchange information, as she did not have damage to her car, so she left the scene. I drove the car home (2 miles from my house) and called the dealership. They told me to bring the car in. I brought it in the same day. Raymond, the service agent came outside to survey the damage and I told him what happened. He went to talk to the service manager and later came out and said they will take the car and put it on the machine to get a diagnostic reading to see why the car stalled. They gave me a loaner car and I left. On Monday, 9/19/17, I returned to the dealership after I got off work and was told by raymond that they could not find anything wrong thus far. He said he wanted to keep the car another day or two to take it for a drive and try to see if it would stall again. I agreed and asked raymond to also check the fuel injectors, fuel pump, fuel regulator, as my friend who is a car mechanic suggested to me that this can cause a car to stall also. He said okay. On today, Wednesday 9/21/17, raymond called me and said they took the car out for a drive and it did not stall, nor could they get a reading that anything was wrong when they put it on the machine. He said he could not understand why the car would stall. I asked for a diagnostic report and he said he could only give me a copy of the service ticket. I am afraid that this car could stall again and what if it happens while driving -- it could be much worst damage and bodily harm. Please help!.