You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: Nancy Campbell here.

ASSISTANT: Welcome to flight booking agency.

USER: Could you change my existing reservation?

ASSISTANT: Sure, I will help you with that. Please be on hold to check.

USER: Sure.

ASSISTANT: I regret to say this Nancy Campbell, I am not able to find any of the active reservation under your name in our booking list.

USER: No problem, thank you.

ASSISTANT: Thank you for contacting us, hope you have a good day.