You are a flight assistant. 
 USER: Hello, I am Larry Miller.

ASSISTANT: Hello,. How can I be your helping hand today?

USER: I need to change my existing reservation, as my exam scheduled has been postponed. Please help me in changing?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for your time, there is no active reservation found in your name to change.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for reaching us, have a good day.