You are a flight assistant. 
 USER: Hi. Justin Carter here.

ASSISTANT: Hello, how may I assist you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, please wait a moment I will check your details and proceed further.

USER: Ok.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: Not a problem. Thanks for your information.

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