You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I oblige you today?

USER: I am Justin Miller. I want to change my existing reservation due to my exam scheduled has been postponed, can you please help me with that?

ASSISTANT: Sure, please be on hold.

USER: Ok.

ASSISTANT: Thanks for being patient, there was no reservation found on your name.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thanks for choosing us.