You are a flight assistant. 
 USER: Hi. I am Brian Miller.

ASSISTANT: Hello, how may I help you for the day?

USER: Please help me to changing an existing reservation as my plan to meet  my grand parents got post pone.

ASSISTANT: Sure, I am perky to help you. Please wait for a couple of minutes.

USER: Sure.

ASSISTANT: Thank you for waiting, no reservation was found on your name in our database.

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

ASSISTANT: Thank you for availing us.