2014 Hyundai Sonata Seats Problems

The driver's seat lost a bolt and the seat was no longer bolted down at the back, although sitting on it would lower it. I took it to a mechanic and they re-attached the screw and bolt but were unable to do so in a way that the seat operates properly. It still lifts when I get out of the car and lowers when I sit down. This is available for inspection if needed. The safety concern is that in the event of an accident, the seat may detach from the base of the car. The problem has been reproduced by an independent service center. The work was done in Feb 2022. The vehicle hasn't been inspected by any others. There were no warnings or other symptoms before or after the event.