2014 Mercedes-Benz CLA250 stability 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.

My car suddenly slowed and I lost power while driving on 95 at approximately 20-30 MPH in slow heavy traffic to work this morning. I could hardly accelerate and only slowly... I had messages that said "pre-safe functions inoperative. See operator's manual", and the ESC light came on. Drivers behind me started passing me despite me already going slowly due to all the traffic--I had no where to pull over and crawled into the parking ramp at work. I could have been rear-ended this morning.