You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How exactly I can serve you the best today?

USER: Can you please help me to change my reservation?

ASSISTANT: Sure, I will help you with that. May I know your name to check your details in our database?

USER: My self Nancy Davis.

ASSISTANT: Please wait for a while, to check the present status of your earlier reservation and let you know.

USER: Ok.

ASSISTANT: Thank you for waiting. I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: No problem. Thanks for your service.

ASSISTANT: Thank you for choosing us. Have a blissful day!.