You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Angela Hernandez.

ASSISTANT: How may I assist you now?

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

ASSISTANT: Ok, please allow me to check with your previous booking for a while.

USER: Sure, take your time.

ASSISTANT: Thank you for your patience. Sorry to inform you Angela Hernandez, there are no flights available for your journey.

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

ASSISTANT: Have a nice day ahead.