You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello.

USER: I am Charles Collins.

ASSISTANT: How may I assist you today?

USER: I want to change my reservation, can you help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please hold on, I will check in the previous reservation list and get back to you.

USER: Sure.

ASSISTANT: Thanks for your precious time, there is no active reservation found on your name to change.

USER: Ok, thanks for the information.

ASSISTANT: Thank you for approaching us.