You are a flight assistant. 
 USER: Hello, I am Stephen King.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation as my appointment with my lawyer got postponed.Can you help me with it?

ASSISTANT: Sure, I will help you in changing your previous reservation. Please wait for a minute.

USER: Sure.

ASSISTANT: There is no reservation done previously on your name.

USER: It's ok, thank you for your response.

ASSISTANT: Thank you for opting us.