You are a flight assistant. 
 USER: Hi, I am Mary Scott.

ASSISTANT: Hello, how may I oblige you today?

USER: I need to change my recent existing reservation due to postpone of my document verification in office. Can you help me in change an existing reservation?

ASSISTANT: Sure. Can you please wait for a moment, I will check with your reservation.

USER: Ok.

ASSISTANT: Thank you for waiting. I have checked in reservation list, but could not find any reservation with your name.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.