Starter Relay problems of the 2008 Dodge Grand Caravan

Going high speed, engine suddenly stops, all lights on dash light up, power steering does not function. This happened (3) times last year. I was fortunate enough to be able to pull over on the PA turnpike but was in danger of being hit as I was traveling in the left lane. Car would not restart. Waited 20 minutes and car did initially restart. However, when it restarted, once driven, it would not shift gears--it was stuck in 1st. (automatic transmission) pulled over again. Waited 10 minutes, started driving, and car functioned but "check engine light" was on. Car was taken to dealer immediately. They initially blamed the fob, which I replaced. When this incident happened again a few months later, it was again taken to dealer and since they could not replicate the problem, they said they could not fix it. In July of this year, started this behavior again but now would not restart after the engine cut off. (again traveling high speed) then the engine cut off a day later while only going 40 miles an hour. Took car to the dealer again and they changed the win module. (but tell me that all three electrical system are registering errors) I paid to replace win module, had car for 1 week, went to start it and there was no response. Had car towed to dealership. Replaced starter relay. Picked car up on a Wednesday and on Thursday, engine shut down on me while doing 20 mph. Again, would not restart. Car currently at dealership but they claim they have no idea what's wrong. This is a hazard!! I feel I am going to die in this car because someone is going to run into me at high speed when I don't have a engine to get out of the way. My young kids are constantly in this car. Dealership throws up their hands and says "I don't know or care if you die in this vehicle we simply can't fix the problem" I am still paying this car off and can't afford another car!.