You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Due to change in my plans to visit Dallas, I would like to change my existing reservation. Can you help me with this?

ASSISTANT: Sure, I will help you about it. But can you please provide the name on which reservation is done.

USER: My name is Carol Hernandez.

ASSISTANT: I have checked in our database there is no reservation under your name Hernandez.

USER: Ok, not an issue. May be something went wrong while booking.

ASSISTANT: Yes, it might be the reason.

USER: Thank you for providing information.

ASSISTANT: Thank you for choosing our service.