You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Melissa Moore.

ASSISTANT: What shall I oblige you for the day?

USER: I want to change my existing reservation due to health issues.

ASSISTANT: Ok. Wait a while, I will check and let you know the status.

USER: Sure.

ASSISTANT: Thanks for waiting. I did not find any reservation on your name to change.

USER: Not an issue, thank you for your good service.

ASSISTANT: Thank you for picking us, have a pleasant day.