You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you for the day?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: May I know your good name please?

USER: Myself Melissa Wilson.

ASSISTANT: Sorry, there is no reservation found on your name to change it.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us, have a nice day.