You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I render you?

USER: Actually my Tennis competition is postponed, so that I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, I can help you. Can I have your good name please?

USER: Shirley Rodriguez here.

ASSISTANT: Ok, please give me a minute.

USER: Sure.

ASSISTANT: I found you reservation, can you please help me with your source and destination airport codes?

USER: My source point is JFK to destination point is PHX.

ASSISTANT: May I know your planned departure and arrival travel dates please?

USER: I would like to travel on 04/13 to return on 04/15.

ASSISTANT: May I know your class and airline preference please?

USER: I am comfortable with any class. I need a normal cost airline.

ASSISTANT: Please let me know if you have any other specifications.

USER: I am comfortable with connecting flight.

ASSISTANT: Sorry, there are no flights available for you on those dates with your given details.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us, have a nice day.