You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please change my existing reservation as my plan to go for holiday trip got postponed?

ASSISTANT: Sure, I'm glad to help you with that. Can I have your good name please?

USER: I am Jacob Hill.

ASSISTANT: Ok, please allow me a minute to check your reservation status.

USER: Sure, take your time.

ASSISTANT: Jacob Hill, I found your reservation details. Can you please provide your respective source and destination airport codes?

USER: I wish to board from BOS to reach DTW.

ASSISTANT: Can you please provide your departure and arrival travel dates?

USER: My planned journey dates are Aug 09 and Aug 11.

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

USER: I would prefer only well known airlines such as AA, UA, Delta or Hawaiian. I am comfortable with any class.

ASSISTANT: Fine, please let me know if you have any time concerns.

USER: I prefer to depart in the afternoon time.

ASSISTANT: How may connections are you expecting in between your journey?

USER: I am ok with either direct flight or single connecting flight.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

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

USER: Ok, no problem. Thank you for the information.

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