You are a flight assistant. 
 USER: Hi, I am Catherine Jackson.

ASSISTANT: Hello, how may I oblige you today?

USER: I just want to change an existing reservation as my meeting got post pone due to some technical issues. Can you please help me with this?

ASSISTANT: Sure, we are rapturous to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT:  Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.