Getting a flu show is Complicated?

I called the doctor's office a week ago to arrange for a flu shot, which had already been paid for. I was stunned to hear that it isn't that simple.  In fact,  said the woman I talked to, "It's complicated."  I should have learned, do not pay for anything before you get it.

I am going to call again today and if I can't get satisfaction I could possibly lose my temper.