You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Brenda Johnson here.

ASSISTANT: How can I assist you for the day?

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

ASSISTANT: Sure, I will help you with that clanging. Please hod for a moment, let me check  your previous reservation status.

USER: Sure.

ASSISTANT: Sorry to say, there is no active reservation found with your name to change it.

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

ASSISTANT: Thank you for contacting us, have a great day.