You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am John Martinez.

ASSISTANT: How may I abet you today?

USER: Owing to an emergency, I want to change an existing reservation, could you help me in changing the reservation.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: I regret that there is no reservation found on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for availing with us.