You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Matthew Lee here.

ASSISTANT: How can I assist you?

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

ASSISTANT: Sure, please be on hold. There is no reservation found under your name to do modifications in that.

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

ASSISTANT: Yes, may be. Thank you for choosing us.