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

ASSISTANT: Hello, how may I aid you today?

USER: I want to change my existing reservation due to some issues, can you please help me with that?

ASSISTANT: Sure, we are glad to help you. Please wait for a while.

USER: Sure.

ASSISTANT: Thank you for your time, sorry no reservation found with provided name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for opting us.