Why is the woman calling the delivery company?

M: Hello, National Express Courier Company, Customer Service Department.
W: Hello, I have some questions about a package I’m going to send, can you help me?
M: Yes, ma’am. What would you like to know?
W: I have a box of homemade candy. And I want to send it to my sister, it’s a birthday present. Do you have any special rules about delivering food?
M: No, not in this case, ma’am. If you were sending fruit or vegetables, they would have to be packed specially. But there are no rules about sending candy.
W: OK, I have another question. I’m very concerned about the package reaching my sister on time. Can you make it sure that it will be there by her birthday on Saturday?
M: Where does it have to go?
W: California.
M: Hmm. Saturday’s only four days away. We have a priority service that would guarantee delivery in three days but it’s more expensive than our regular rate.
W: Well, I don’t want to waste money, but it’s more important that the package be there on time.
M: OK. Bring your package to the office, and we’ll send it by priority service.
W: OK. I’ll do that.