Navigational (global Positioning System) Gps problems of the 2015 Hyundai Santa Fe

While driving my car on the highway, the entire electrical system shut-down including my cruise control, gps, radio etc. Also on this same trip, the engine completely stopped (also while on the highway). Luckily I was just turning off an exit ramp and was able to barely steer it to the side of the road. The starter light was still on, but the vehicle was completely dead. Had to punch the starter light again to turn it off and then back on again. A second incident occurred while my husband was driving my car in the city just this past week. Driving on streets (not highway driving) and the car shut down unexpectedly 4 different times: once climbing a hill; once trying to pass another driver; twice for no reason. I've taken this to the dealer since it's still covered under extended warranty but since they can't find any issues, the next time I take this in it will cost me money. Of course, since the engine completely stops, nothing is recorded with sensors or computers. Help please.

The screen on the gps unit cracked as I was cleaning it. I had the car for 10 months with 7000 miles on the car. Hyundai has refused to replace the unit. I am unable to download updates, the continuity is broken. The car was parked and in my driveway as I was cleaning it.