You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can 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, please share your name.

USER: Sure, I am Nancy Walker.

ASSISTANT: I could not found any reservation on your name to change.

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

ASSISTANT: Thank you for opting us.