You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Charles Anderson.

ASSISTANT: Yes Anderson.

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

ASSISTANT: Sure, I will help you to change your reservation. Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation found on your name to change your existing reservation.

USER: That's ok.

ASSISTANT: Ok. Thank you for choosing us.

USER: Thank you for your information.

ASSISTANT: Welcome.