You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. What type of help that you are expecting from my side?

USER: I am Samuel Harris. I want to change my existing reservation due to postpone of my exams so, can you please help me with this?

ASSISTANT: Sure, please be on hold for a moment to check your booking.

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: Not a problem, thank you for the information.

ASSISTANT: You are most welcome.