The faculties
The faculties have authority over anything that involves academic judgement or otherwise requires subject matter (discipline) expertise.
This extends from any decisions regarding admission to the degree you’re studying, decisions about advance standing or credit, any equitable adjustments or alternative arrangements due to Special Consideration and the design and grading of assessments for the subjects you’re enrolled in.
Subject or course coordinators
Subject or course coordinators are usually a good place to start if you have any questions but it’s important to know that although they’re experts in their discipline, they are not necessarily experts in the administrative aspects of how the University organises itself. Nevertheless, start with them, especially if something is related to the subject matter of your course. You can find your subject or course coordinator in the handbook (which you should have bookmarked).
Things can start to get tricky regarding extensions and Special Consideration. Short extensions are handled directly by the faculty and so subject coordinators are a good source of information for those questions. But you can also ask Stop 1 about broader options beyond just a short extension.
Special Consideration is managed by a unit which is part of Student and Scholarly Services (SASS), but you won’t generally be able to engage with them directly.