A department chair is a faculty member who splits their time between teaching their classes and managing their department. That includes scheduling classes, assessing the effectiveness of the courses in their program, hiring instructors, and a myriad of other duties.
A dean manages an academic center that includes many different programs. They lead the academic, budgetary, and administrative functions of the center – providing leadership and vision.
Anytime a student has an issue in a class, they must first try to resolve that issue with their instructor. When that does not work, they should contact the department chair over that program. This list gives you those names. If you still have an issue, you can then contact the dean over that program, and their names are also listed here.