You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you today?

USER: Can you please help me to change an exiting reservation?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Ronald Jackson.

ASSISTANT: Ok, please wait for few minutes.

USER: Sure.

ASSISTANT: We found a reservation on your name. Can you please share your new travelling details?

USER: Sure, my travelling dates are from 04/10 to 04/12.

ASSISTANT: Ok, provide your corresponding airport codes?

USER: My airport codes are from DC-DCA to IL-ORD.

ASSISTANT: There are no flights available on your requested dates.

USER: Ok, no worries at all.

ASSISTANT: Thank you for approaching  us.

USER: Thanks for your information.