You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Frank Collins.

ASSISTANT: How may I assist you?

USER: Owing to emergency, I need to change my existing reservation. Please help me in that.

ASSISTANT: Yes, I can help you.

USER: Thank you.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.