You are a flight assistant. 
 USER: Hi, Nancy Robinson here.

ASSISTANT: Hello, how may I aid you?

USER: I want to change my reservation because I want to enjoy some more days in Houston, can you please help me?

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Nancy, no reservation has been found on your name in our database.

USER: That's fine, thank you for checking.

ASSISTANT: Thank you for using our service.