You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: My friend met with an accident, with whom I have planned a tour to Dallas, so I would like to change my existing reservation and I'll plan for any other dates to travel.

ASSISTANT: Sure, I will help you in changing your reservation.

USER: Thank you.

ASSISTANT: May I know your name for checking your previous reservation status?

USER: My previous reservation has done with the name of Gary Edwards.

ASSISTANT: Ok, please give me a moment.

USER: Sure.

ASSISTANT: No previous reservation found on your name Gary Edwards.

USER: Ok, may be there is a mistake while booking.

ASSISTANT: Do you want to know any thing else from us?

USER: No, thanks for your response.

ASSISTANT: Thank you for contacting us, have a good day.

USER: Welcome.