日常生活英语-Calling Credit Card Company(3)

A: I was inquiring about a bill that I never got.
B: Which credit card was the bill for?
A: The bill was for my Master Card.
B: That bill should have been mailed about two weeks ago.
A: It never came in the mail.
B: My computer shows that it has already been mailed.
A: I have not gotten my bill, so what should I do about that?
B: You should try contacting your post office.
A: If it is the post office's fault, may I have an extension on my bill?
B: You'll have to prove it was their error; then you can get an extension.
A: Thank you for all your help.
B: You are very welcome. Have a good day.