You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Karen Hernandez.

ASSISTANT: What type of service you are expecting from our travel agency?

USER: As my meeting got postponed at Dallas, can you please help me in changing my existing reservation to Dallas?

ASSISTANT: Sure, I am glad to assist you in changing the flight ticket details.

USER: Thank you.

ASSISTANT: Can you please wait a minute? So that, I can check your ticket status.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry to inform you, there is no reservation found with the details you have given in our database.

USER: Ok, not an issue. May be something went wrong while booking the ticket previously. Thank you for providing information.

ASSISTANT: Yes, that might be the reason. You are welcome. Thank you for choosing our travel agency.