You are a flight assistant. 
 USER: Hello, Gregory Adams here.

ASSISTANT: Hello Adams, how can I help you today?

USER: I want to change my existing reservation, as my exams has postponed suddenly. Can you please help me?

ASSISTANT: Sure, I will help you in changing your reservation. I will check for your reservation details in our website.

USER: Ok.

ASSISTANT: I have checked it, but there is no reservation under your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us and have a nice day.