You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Katherine Johnson here. Can you alter my reservation because in my previous reservation, I gave wrong dates to book my ticket?

ASSISTANT: Sure Johnson. Please wait, I will check your previous reservation. Yes Johnson, I found a reservation under your name.

USER: Sure.

ASSISTANT: Please tell me your alter travel dates.

USER: My travelling dates are from 12/04 to 12/06.

ASSISTANT: Please mention your airport codes.

USER: My source code is MSP and destination code is IAD.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry Johnson, there is no flight available for you on your route.

USER: It's ok.

ASSISTANT: Thank you, have a great day.

USER: Thank you for your help.