Brakes Failed problems of the 2016 Hyundai Elantra

The brakes on my Hyundai Elantra failed twice within 10 minutes. I was driving on a highway with stoplights. I had ample time to stop under normal conditions, but with the brake pedal down to the floor, the car would not stop in time for a stop light and even went all the way through the intersection before stopping. It was also not handling normally during the moments when the brakes failed. Fortunately there was not another car or pedestrian in my path. I stopped and checked to see if the floor mat had bunched up under the pedal. It had not. Thinking it might just be a fluke I proceeded to drive home very cautiously. Driving under 50 mph, and testing the brakes, they seemed to be working. When I was approaching another stop light I slowed down to maybe 35 way in advance. Then the light changed to red and again the car was extremely slow to stop. I was able to stop it just before the light but only because I was already going very slow, anticipating a possible problem. I have noticed that there was a recall for a brake problem for Elantras a little newer than mine. That was for a brake booster. Reading the first hand accounts of those failures, is very similar to what I experienced. Since only the recalled vins had the part that was manufactured by mando, and my brake booster was evidently made by another manufacturer, but my experience with the brakes was so similar to the recalled vehicle, I worry that the problem with all those cars could actually be a design flaw in the car or another part that interacts with the brake booster. My car is currently at a Hyundai dealership. They are still working on diagnosing the problem. It has been there three days. I am very worried about driving the car in the future after it is fixed.