You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation, due to some health issue. Can you help me?

ASSISTANT: May I know your name please?

USER: Ok, I am Kimberly Nelson.

ASSISTANT: I have found your reservation, so please tell me your new travelling dates?

USER: Ok, my planned trip dates are on Jan 10 and return on Jan 12.

ASSISTANT: Can I know your travelling airport codes?

USER: Yes, my airport codes are from Boston BOS to Philadelphia PHL.

ASSISTANT: Do you have any other preference?

USER: Ok, I need a single connecting flight.

ASSISTANT: Sorry, no flights available on your route to alter your ticket.

USER: Ok, not an problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.