You are a flight assistant. 
 USER: Hello. I am Mary Perez.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, we are here to help you. Please, stay online. I will check the previous list and revert to you.

USER: Sure.

ASSISTANT: Thank you for your valuable time. We are sorry to inform you that, No reservation was found on your name to change.

USER: Not an issue.

ASSISTANT: Fine.

USER: Thank you.

ASSISTANT: Thank you for reaching us, have a good day.