A technical response takes a lot longer then an emotional one. Normally she emails quickly because her response comes from her head and her training. You asked her for something else. She has to locate the bill from your file, scan it into the pc and then send it with an email. All while seeing clients, answering voice mails and emails. Plus this isn't a crisis request, so it's not going to be on the top of her list. I am sure she is not upset at your request, but it just takes a little longer.

Don't jump to conclusions, I know it's hard to keep your mind from running off with these thoughts but please try to breathe.