Use ～ものだから when you want the listener to accept your reason — it frames the cause as something beyond your control, so it naturally carries the tone of an excuse or apology. In business it appears constantly in the polite form ～ものですから when explaining a delay, an absence, or a request for leniency. Unlike ～から, it cannot be used to justify a command or invitation, and unlike ～ので it always sounds subjective and self-defending.