You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Ok, please can I know your name to proceed further?

USER: Dennis Garcia.

ASSISTANT: Ok, please be on hold while I check the records of reservation.

USER: Sure.

ASSISTANT: Sorry, there is no reservation been found on your name to amend it.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing our agency.