You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: Please help me in changing of my existing reservation due to health issue.

ASSISTANT: Sure, may I know your name?

USER: Samantha Mitchell.

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

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thank you.