Another answer is perhaps more likely. Experienced Bapak and their assistants may understand the frustration caused by the canceling and rescheduling of meetings that is so common in traditional Indonesian business culture. Accept the possibility that you are not informed until just before an important meeting to spare you inconvenience. It could be a sign of respect that you are not asked to keep rearranging your schedule to meet the fluctuating time constraints of the Indonesian participants. You are only informed when everyone else is sure that the meeting will actually proceed.
Effective communication is a two-way street.
This is especially true in intercultural work environments. The rationale and feelings behind an action in Indonesia are often different than the rationale and feelings behind a similar action in your home country. One has to communicate more openly here. Control your emotions and explain what changes you would like to see. This may or not be effective.