You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you at this moment?

USER: I would like to amend an existing reservation, can you please help me?

ASSISTANT: Ok, I will help you with that.

USER: Thank you.

ASSISTANT: On whose name the ticket was booked?

USER: Sure, I am Larry King here.

ASSISTANT: We are happy to inform you that the reservation is found.  Can I know your planned trip dates?

USER: Sure, my planned travelling dates of journey are from Jul, 19 to Jul, 21.

ASSISTANT: May I know your airport codes?

USER: Sure, my recent airport codes are DCA and PHL respectively.

ASSISTANT: Please wait for a minute.

USER: Sure, I will wait.

ASSISTANT: May I know your airline preference?

USER: I prefer to fly in big brand airlines.

ASSISTANT: Ok, do you have any connection limit?

USER: Yes, I prefer to go with a connecting flight.

ASSISTANT: Ok, wait for a minute.

USER: Sure, I will wait.

ASSISTANT: Sorry to inform you that, there are no flight's available based on your journey details.

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.