You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I serve you?

USER: Due to some health issue from last night, I am unable to travel now. Can you please change my existing reservation?

ASSISTANT: Sure, May I know your name?

USER: Sure, I am Nicholas White.

ASSISTANT: Please wait a second.

USER: Ok, I will wait.

ASSISTANT: Sorry, No reservation found on your name.

USER: Ok, Thank you for your help.

ASSISTANT: Thank you for opting us.