You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I have to change my reservation as my meeting got postponed, so please help me to change.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: On whose name, the reservation has been made earlier?

USER: Sure, I am John Williams from Philadelphia.

ASSISTANT: Please wait for a while.

USER: Sure.

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

USER: No worries, thank you.

ASSISTANT: Thank you for reaching us.