You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: I am Dennis Thomas. Owing to an emergency, I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, please wait for a minute.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.