You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I render you today?

USER: I am Ryan Scott. I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Sure, I'll help you in changing an existing reservation. Please wait a moment.

USER: Sure.

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

USER: Ok, no problem.

ASSISTANT: Thank you for opting us.

USER: Thanks for your information.