You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you?

USER: I want to change my existing reservation, due to some health issue. Can you help me?

ASSISTANT: Sure, I am here to help you. Can you please tell me your name?

USER: Thank you. I am Steven Williams.

ASSISTANT: Ok, please give me a minute.

USER: Sure, take your own time.

ASSISTANT: I am really sorry to inform you, there is no reservation found with your name to change the details.

USER: Ok, not a problem. Thank you for your help.

ASSISTANT: You are welcome. Thank you for opting us.