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

ASSISTANT: Hello, how may I assist you today?

USER: My meeting got postponed as of now, so I need to change my existing reservation. Please help me in changing?

ASSISTANT: Sure, we are glad to serve you. Please wait couple of minutes.

USER: Ok.

ASSISTANT: Thank you for your valuable time, unfortunately no reservation found on your name.

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

ASSISTANT: Thank you for availing us.