answer: #Person1# isn't satisfied with the product. #Person2# needs to see the receipt to give the money back.
documents: #Person1#: I'm not satisfied with it.
  #Person2#: Why not? What's wrong with it?
  #Person1#: Sometimes it goes fast and sometimes it goes slow, and the alarm doesn't work either.
  #Person2#: Would you like another one?
  #Person1#: No, can I have my money back?
  #Person2#: Emm, have you got a receipt?
  #Person1#: A receipt?
  #Person2#: Yes, I must see your receipt. You can't have your money back without a receipt.
  #Person1#: Though I'm not certain, but I think I've lost it.