You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: My name is Betty Harris and I would like to change an existing reservation.

ASSISTANT: Sure, I am here to help you with this.

USER: Please do the needful.

ASSISTANT: Sorry Betty, there is no reservation found as per your name to change it.

USER: No problem. Thank you for the help.

ASSISTANT: You are welcome.