Car Slowed Down On Its Own problems of the 2011 Kia Motor Optima Hybrid

While driving (in forward motion), without any pressure being applied to either the brake or parking brake, the vehicle begins to slow itself rapidly losing acceleration. ; a rumble can be heard there is consistent beeping noise and the vehicle begins to vibrate slightly. A yellow triangle with an exclamation point and the words check brakeappears in the drivers display; attempts to accelerate increases the rpms but the vehicle continues to slow rapidly. Not idle as if it were not in gear, but just as if the driver was breaking suddenly. The only known method of correcting this is to turn the vehicle off and restart it. However, this stops working as a solution after a few days and the problem persists. When the vehicle restarts you can feel the brake pedal release. This has occurred randomly at least 20 times in the past before until eventually it could not be driven at all. At speeds ranging from 25 mph on neighborhood streets to 70 mph on busy freeways. I sincerely fear that if not corrected it will lead to a (potentially fatal) vehicle collision. I also took the vehicle to a near-by kia dealer service department in CA. After months the car was returned and it continued ot have the same issue within a days. They were unable to diagnose or duplicate the malfunction as also. I have video of this as well. This needs to immediately be corrected and the technicians need to know what the problem is and how to fix it rather than experimenting on owners vehicles for months or weeks to then return it without resolution. Why should I or any other kia owner bear the burden of these unnecessary costs, inconvenience, and extremely unsafe conditions. Kia needs to respond I am sure others have experienced this same issue and should come forward immediately for the safety and well being of all.