You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: Because of some health issues, I want to change my existing reservation, can you please help me in this/.

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, my name is James Martin.

ASSISTANT: I am sorry to say that there is no reservation found.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing our agency.

USER: Thank you for your service.

ASSISTANT: Have a great day.