You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Myself Carol Harris from Las Vegas. I want to do some changes in the existing reservation because my friends are not able to come on the those dates. Can you please help me with that?

ASSISTANT: Sure, please wait a moment I will check your details and proceed further.

USER: Ok, thank you for your positive response.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: Oh! It's ok no problem.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Thank you for your information.