You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my exam dates. Can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: Elizabeth Allen here.

ASSISTANT: I have found your reservation, can I know your travelling airport codes?

USER: My airport codes are ORD to PHL.

ASSISTANT: May I know your travelling dates?

USER: My travelling dates are Oct 17 to Oct 19.

ASSISTANT: Do you have any requirements?

USER: I need a single connection of flight.

ASSISTANT: Sorry to say, no flight is available for you. Thank you for reaching us.

USER: No problem, thanks for your information.