You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: I am Ruth Phillips.

ASSISTANT: Ok, please wait for sometime.

USER: Sure.

ASSISTANT: We found reservation on your name, please provide your airport codes?

USER: My airport codes are DCA and MSP.

ASSISTANT: May I know your travelling dates?

USER: I prefer to travel on Aug 27 and Aug 29.

ASSISTANT: Do you have any connection limit?

USER: I prefer to travel in a connecting flight.

ASSISTANT: Any other requirements to be met?

USER: I would like to depart in afternoon.

ASSISTANT: Sorry, there are no flights found with your given details.

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

ASSISTANT: Thank you for reaching us.