Whenever I get some "newbie" to my cars I look 'em in the eye and tell 'em this, "This [Porsche 914 or VW Squareback] is an old car. You don't need to slam the doors shut. Anything you can adjust, for example, a window crank, you do so gently and smoothly. If you feel resistence or it stops, you stop and don't try to force it, because you'll break it and you don't want to know how much replacement parts cost."
Short, to the point, but let 'em know to be gentle
Sorry about the breakage but at least that is common (happened to both of my teeners...by ME
) and there's an after-market replacement for it