You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: I need to change my existing reservation owing to an emergency.

ASSISTANT: Sure, we are mirthful to help you. May I know your name?

USER: My name is Joseph Garcia.

ASSISTANT: We regret to inform you that there is no active reservation found on your name to change.

USER: Thank you.

ASSISTANT: Thank you for contacting us.