You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Barbara Carter.

ASSISTANT: How can I help you now?

USER: I want to change my existing reservation due to some problems, can you please help me in changing the reservation?

ASSISTANT: Sure.

USER: Ok.

ASSISTANT: Please wait a moment, I will check your details in our database and revert and rever back to you.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Ok no problem, thank you for your information.

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

USER: Have a great day.