You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know your good name please?

USER: I am Alexander Nelson.

ASSISTANT: How can I help you today?

USER: I want to change my existing reservation due to my convocation date has been changed.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, we have no reservation found on your name to change.

USER: Not an issue. Thank you for kind information.

ASSISTANT: Thanks for choosing us.