You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you for today?

USER: Can you please change my existing reservation?

ASSISTANT: sure, I will help you about it. Can you please provide the name on which your previous reservation is done?

USER: Myself Donna Adams.

ASSISTANT: Sorry Adams, there is no reservation under your name in our database.

USER: Ok, fine. Thank you for your information.

ASSISTANT: My pleasure, thank you for opting our service. Hope you have a great day ahead.