2014 Mercedes-Benz CLA250 cruise control problems

Purchased a mercedes cla 250c, and have had it became inoperative while driving on the beltway in washington d.c. Traffic, and more recently on the I-5 in san diego on 1/21/2017 during rain at speeds of 60+ MPH in heavy traffic. The vehicle decelerated quickly and lost speed. The console popped up flashing message 'pre-safe functions limited' on the console. The vehicle did not respond to accelerator.

I was driving on a busy surface street in los angeles when my car lost all acceleration and the message popped up, "inoperable, see manual". I tried to push the gas pedal to quickly move over to the right lane where I could put on my hazard lights but I could not accelerate. I turned off the car quickly and started it again and it went back to working for now. I am terrified for this to happen again, especially because if it happened on a los angeles freeway, I could easily be killed.