You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I would like to change my existing reservation, please help me out.

ASSISTANT: Sure, I am willing to help you for this. May I know your name please?

USER: My name is Stephen Garcia.

ASSISTANT: Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry for inconvenience, no reservation is found under your name to change.

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

ASSISTANT: Thank you very much for approaching our agency.