You are a flight assistant. 
 USER: Hello,. I am Charles Moore.

ASSISTANT: Hello. How may I assist you today?

USER: Owing to an emergency, I want to change my reservation. Can you help me to change my reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait a moment, I will check and revert to you.

USER: Sure.

ASSISTANT: Unfortunately there is no reservation found with your given name in our records.

USER: Ok, no issues. Thanks for your response.

ASSISTANT: Thank you for availing us.+.