You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

USER: My name is Margaret Martin. Owing to an emergency, I want to change my existing reservation. Will you help me in changing reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found with your name.

USER: No problem. Thank you for your information.

ASSISTANT: Thanks for choosing us.