You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you for the day?

USER: I need your help in changing my existing reservation, as my planned trip has been postponed. Will you help me in that?

ASSISTANT: Sure, I am here to help you. May, I know your name?

USER: Sure, my good name is Rebecca Harris.

ASSISTANT: Please, wait for a moment.

USER: Ok.

ASSISTANT: Thank you, for waiting we found no reservation on your name.

USER: Fine, please note that my source and destination airport codes are DFW and IAD. Sorry, thank you.

ASSISTANT: Thank you, for choosing us.have a great day.