Moments before suspected SUA accident on the Guri-Pocheon Expressway, 2019.05.01

This is a video of an accident near the Shinbuk TG on the Guri-Pocheon Expressway in the direction of Pocheon on May 1st.
I posted a few days ago that I was looking for black box footage, and after much thought, I decided to upload the footage from my car's black box.
Please watch the video and get some advice from experts.

Details of the accident
Rapid acceleration begins before entering the Shinbuk tollgate, and the vehicle becomes uncontrollable.
After avoiding other cars and entering the shoulder to avoid an accident in a traffic jam, the car first collided with the Carnival, then got stuck between a tanker truck and the shoulder and stopped.

Vehicle contents
Santa Fe DM, July 2012 model, mileage approximately 70,000 km
The last maintenance (69,719 km) was a free DPF warranty repair at a Hyundai Motor Company dealership on March 22, 2019.
After maintenance, it was hardly driven and the accident occurred at 70,000 km.

The black box audio shows that the brakes were not working, the engine could not be turned off, and acceleration continued.

Looking at the warranty repair contents, I see items such as exhaust-related parts, EMS box replacement, and box assembly-engine module system.
I would like to ask for advice on whether this phenomenon can occur after replacing the DPF.

My father, who was driving the car, is currently unconscious, and my mother, uncle, and aunt, who were in the car, are seriously injured and are currently hospitalized.

We apologize for not being able to mosaic the license plates of other vehicles due to the urgency.

I'm writing this because I feel wronged and frustrated. I ask for your help once again.