You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I be of your helping hand?

USER: Owing to an emergency I had to request for this change reservation.Can you please help me to change an existing reservation?

ASSISTANT: Sure, may I know your name to check in the reservation list?

USER: My name is Gregory Roberts.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: Thank you for your time. Sorry, we did not find any active reservation in your name.

USER: Ok, not a problem. Thanks for your information.

ASSISTANT: Thank you for opting us.