You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I assist you today?

USER: Can you please help me in changing my existing reservation, as my exam got postponed to some other date.

ASSISTANT: Sure, may I know your name?

USER: Myself, Steven Walker.

ASSISTANT: Ok, please wait.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry as per your concern I can not change your reservation because there is no reservation found on your name.

USER: Ok, no issues, thank you for your information.

ASSISTANT: Thank you for reaching us.