You are a flight assistant. 
 USER: Hi. I am Katherine Lopez.

ASSISTANT: Hello, How can I serve you the day?

USER: I would like to change my existing reservation, my meeting has been postponed. Could you please help me?

ASSISTANT: Sure, I will help you with that. Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting. We regret that, there is no reservation on your name to change it.

USER: Ok, no issues.

ASSISTANT: Thanks for your response.

USER: Thank you for your information.