general problems of the 2011 Nissan Leaf

About a month and a half ago, I purchased a 2011 Nissan Leaf from my local dealer. Everything was going great until about a month ago when I was driving on the highway around 20 mph or so when the power suddenly shut off. The entire dashboard instantly went off but the radio+touchscreen remained on. The car came to a crawl and I was able to pull over and restart without any problems. It was a little scary to say the least. I called the dealership where I bought the car from and left a voice mail for the service dept. Since it was Saturday but never received a call back. I kind of shrugged it off that day thinking it might have just been a quirk so I didn't follow up with the dealer. About a week and a half ago, I was pulling into a parking lot going around 10 mph and the same thing happened. I called the dealership and took it in the next day. They've had the car for about a week and said that Nissan told them to drive it and try reproducing the problem. I didn't expect them to reproduce it since it has only happened twice within weeks. As expected, they couldn't reproduce it so I was told that I would have to take the car back since they couldn't do anything about it. I am taking the Leaf back tomorrow to start driving again but definitely have concerns since my wife also drives the car and who knows what she would do in a shut-off while driving situation. Luckily, the past two incidents were not in high speeds and I was able to react quickly. My worst nightmare would be if we got rear ended due to instantly losing power. I have called Nissan directly to let them know about my car but no one has called me back. I assume they were already in touch with the dealer. I don't like the fact that I am being handed the car back at a potential safety risk.