You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my existing reservation due to my board exams are postponed. Can you help me for that one?

ASSISTANT: Sure, may I know your name to check your details?

USER: Sure, Stephanie Lee here.

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: I have found your reservation, may I know your new travelling dates?

USER: Sure, my travel dates are 07/17 and 07/19.

ASSISTANT: May I know your new airport codes?

USER: My travelling airport codes are  ORD to :LGA.

ASSISTANT: May I know your connection preferences?

USER: I need a flight with maximum connection of 1.

ASSISTANT: Do you have any depart and return timings?

USER: Make sure that, my return time should be in morning only. No more specifications please.

ASSISTANT: Sorry to say, no flight is available for you as per your requests.

USER: No issues, thank you for the information.

ASSISTANT: Thank you for reaching us.