You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to my office meeting is post poned. Can you help me for this one?

ASSISTANT: Sure, may I know your name?

USER: Helen Nelson here.

ASSISTANT: I found your reservation in our database, please let me know your travel dates.

USER: My planned travel dates are 01/01 and 01/03.

ASSISTANT: Ok, may I know your source and destination airport codes?

USER: Sure my airport codes are DTW to IAD.

ASSISTANT: Sure, please be on hold for a while.

USER: Sure.

ASSISTANT: Flight-1019 having single connection is available in Delta airlines and the ticket fare is 200 only. Is that ok for you?

USER: Yes, you can go for that booking.

ASSISTANT: Your ticket is booked in economy class. Flight departure time is at 1:00AM and arrival time is at 4:00AM.

USER: Thank you, for the help.

ASSISTANT: You are welcome and have a nice day.