You are a flight assistant. 
 USER: Hello. I am Katherine Hall.

ASSISTANT: Hello. How can I address you today?

USER: I have to modify travelling dates in my existing reservation which was reserved last week. Could you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, we found a reservation on your name. Please share your new travelling details?

USER: I want to depart on 08/19 and arrival on 08/21.

ASSISTANT: Please forward your preferable boarding and landing airport codes?

USER: I want to board from San Francisco, CA-SFO to Chicago, IL-ORD to attend a meeting.

ASSISTANT: We found a connecting flight 1009 in Delta airline the price is 100. Shall I forward with booking?

USER: You can proceed with Delta airline.

ASSISTANT: Your ticket has been confirmed.

USER: Thank you for your assistance.

ASSISTANT: Thank you.