051.
W: Hello, Home & Office Supplies. Can I help you?
M: Yes, it's Thompson Electronics here. We have an account with you.
W: Oh, yes. How can I help?
M: We've just had some printers delivered, but they are the wrong ones.
W: Oh, dear. I do apologize for the mistake.
M: I don't know how you could have got it wrong. We order from you all the time.
W: I know. But unfortunately, we've been having a problem with our computer system.
M: Well, how can we sort this out?
W: Could you bear with me a moment please? Ah, yes, I have the order here. You want 25 HW3C56 printers. Is that correct?
M: Yes, that's right. But you sent us 25 HW56 instead.
W: I see. I'll sort it out right away and we'll post the order special delivery.
M: Thanks.
W: I'll put a $300 credit on your account to make up the inconvenience as well. Is that all right?
M: Oh, that's very nice. Thanks.

答案解析：
(1) wrong
(2) 3C56
(3) system
(4) special
(5) credit