There are several possibilities. One is a failing ignition switch, where the switch contacts do not open as designed. Another is a possible problem is with the accessory power control (RAP) system. Another possibility is damage to the wire harness, something which has plagued more and more vehicles as a result of increasing complexity and downsizing components for material conservation.
Someone will have to invest time to diagnose the problem to determine what is at fault, and that is where the expense of repair is created.