You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you now?

USER: Owing to an emergency, my business conference got postponed. So I want you to change my existing reservation.

ASSISTANT: Sure, I will help you with that. Can I know your name to check your previous reservation?

USER: Sure, Patrick Parker here.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: I have found your reservation. Can you please provide your new journey airport codes?

USER: Sure, I need to depart from CLT to DCA.

ASSISTANT: Ok, may I know your preferable dates of travelling?

USER: Sure, my scheduled dates are Jul 25 and Jul 27.

ASSISTANT: Do you have any connection limit?

USER: I would prefer a direct flight.

ASSISTANT: Any other preferences do you have?

USER: I would prefer a depart time at morning.

ASSISTANT: We are apologize that, there are no direct flights running towards your region with your requested dates of travelling.

USER: Ok, no issues.

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

USER: Thank you.

ASSISTANT: Welcome.