You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am Jeffrey Turner.

ASSISTANT: What type of service do you need from our agency?

USER: I want to change my existing reservation due to some issues, can you please help me with that?

ASSISTANT: Certainly, I am happy to help you in changing  the ticket details. Please be on hold for a minute. I will get back to you.

USER: Sure.

ASSISTANT: I am really sorry to inform you that, there is no active reservation found with your name in our portal to change the details.

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

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