You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I aid you?

USER: I want to change my existing reservation which is with the name Thomas Carter, please help me out.

ASSISTANT: Sure, I am here to help you. Please stand by.

USER: Ok.

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

USER: No problem, thank you for the information.

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