You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Anthony Davis.

ASSISTANT: How can I aid you at this moment?

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

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: There is no previous reservation available on your name Anthony Davis.

USER: That's fine. Thank you for your service.

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