You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, may I know your name?

USER: Sure, please check the reservation on the name of Margaret Walker.

ASSISTANT: Sorry, there is no active reservation on your name.

USER: Ok, Thank you for providing information.

ASSISTANT: Thank you.