You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How may I help you?

USER: Please change my existing reservation owing to an emergency.

ASSISTANT: Sure, please mention your name to check your reservation.

USER: Ok. My name is Margaret Lopez.

ASSISTANT: Thanks for your response, there is no reservation found under your name to change it.

USER: Thank you.

ASSISTANT: Welcome Margaret Lopez.