You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Sure, I am happy to help you and please mention your name for checking.

USER: My name is Thomas Anderson.

ASSISTANT: Please give me a moment to check it.

USER: Ok.

ASSISTANT: Thank you for waiting, I have checked and there is no reservation found for the user name in our data base.

USER: Thanks.

ASSISTANT: You are welcome and thank you for reaching us.