You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: I am here to help you out. Please provide me your name to check you previous reservation details.

USER: Myself Anthony Johnson.

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

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us.