You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: Katherine Nelson here. I need to change my existing reservation due to some health issues, can you help me in doing that?

ASSISTANT: Sure, I am happy to help you with that. Could you please wait a minute?

USER: Sure.

ASSISTANT: I regret to inform you that, I have not found any active reservation under your name in our portal to change the details.

USER: Ok, no issues. Thank you for the information.

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