Someone help...Jury Duty Question?

Okay so my jury duty date is on Tuesday and it was fine even though I'm right in the midst of finals at my school. One of my professors needed to change the date of the test to that Tuesday morning, but I just found out about it a day ago. So I went online to postpone my date and it said that I can't because it's within 7 days of my original date... what the hell do I do? They said to call the comissioner of jurors and I will tomorrow (I tried today but they were closed)... will they still let me reschedule?