You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I have to change my existing reservation, as I am not feeling good. So, will you help me in this for changing the reservation?

ASSISTANT: Sure, I will help you. May I know your name?

USER: I am Christine Hall.

ASSISTANT: Unfortunately, There is no reservation found with your name.

USER: Thank you for helping me.

ASSISTANT: Thanks for choosing us.