You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I have to change my existing reservation due to exam postponed, can you please help me?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name for checking your previous reservation?

USER: Sure, my name is Michael Adams here.

ASSISTANT: Please wait a second.

USER: Sure, I will wait.

ASSISTANT: There is no reservation found under your name to change.

USER: Ok, not an issue.Thank you for your information.

ASSISTANT: Thank you for opting us.