Mysterious button on steering column

Hey. Not sure if this thread is still open. If it is, does that mean that it's a key problem, or an ignition tumbler problem, or a key release button problem? My mechanics have broken the key release button, and now the key just comes out, even if the engine is running. What do I need to do to fix this? Any help appreciated.

It's a key and a key cylinder problem. Fix one or the other for a partial solution. Fix both for a proper solution.