2016 Chevrolet Impala Brakes Problems

My brake assist will come and say “brake assist off”. When pushing brakes my car will skip and the brakes sound crunchy. It’s been almost a couple of weeks of this. I’m concerned safety wise due to the fact it almost didn’t stop. No mechanic shop can help apparently though. Any advice? Please and thank you.

ON 27 APRIL 2021 MY SON IN HIS 2016 IMPALA WAS INVOLVED IN A COLLISION WHEN THE VEHICLE FAILED TO STOP AT AN INTERSECTION. WHILE ATTEMPTING TO STOP THE BRAKE PEDAL SEIZED AND FAILED TO STOP THE CAR BEFORE HITTING ANOTHER VEHICLE. I AM CONCERNED WITH THIS ISSUE BECAUSE I ALSO HAVE A 2016 TAHOE THAT WAS RECALL (N192261050) FOR A BRAKE ISSUE. ACCOUNTS OF THE VEHICLES ACTIONS AT TIME OF INCIDENT ARE EXACTLY THE SAME AS WHAT WAS HAPPENING WITH 2016 TAHOE. WHILE THE 2016 TAHOE HAS UNDERWENT RECALL REPAIR, ITS STILL NOT BRAKING NORMALLY BUT IT DOES STOP ALTHOUGH ROUGHLY. THE DRIVER OF 2016 IMPALA WAS A PASSENGER IN TAHOE THIS PAST WEEKEND AND DURING A ROUGH STOP THE PASSENGER INDICATED "THAT'S WHAT MY CAR SOUNDED LIKE WHEN BRAKES DIDN'T WORK." I'VE REPORTED THE ISSUE TO INSURANCE COPY ASKING THEY THOROUGHLY INSPECT THE VEHICLE AND ALSO REPORTED TO MANUFACTURER.