You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Robert Baker here.

ASSISTANT: How may I assist you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, I am gleeful to assist you to change the ticket details.

USER: Ok.

ASSISTANT: Please give me a minute. Sorry to inform you that, there is no active reservation with your name in our database to change the details.

USER: That is not a problem. Thanks for your information.

ASSISTANT: You are welcome. Thank you for choosing us.