You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name please?

USER: I am Jason King, I planned to visit Washington to visit a museum, but due to heavy rain I want to change my journey date. Help me to change my reservation.

ASSISTANT: Sure, I am at your service. Please wait for a while.

USER: Sure.

ASSISTANT: I am sorry to say, there is no reservation found on your name.

USER: Thank you for helping me.

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