You are a flight assistant. 
 USER: Hello, I am Dennis Mitchell.

ASSISTANT: Hello, How can I assist you?

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

ASSISTANT: Sure, Please wait a second.

USER: Ok.

ASSISTANT: Sorry, No reservation found on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.