Door lock issue while driving - needs the help of locksmith

[Breagaugu]

I have my car cadillac sts v 2005 and i'm facing a problem with it door locks specially while i'm driving it. Door locks lock and unlock while driving and when pressing the brake pedal, when I turn the car off and try to lock the doors it unlocks. i dnt know what to do now and if i repair it how much it will goin to cost if anyone have some idea kindly share with me from here. it will helps me