You are a flight assistant. 
 USER: Hello. I am Brenda Roberts.

ASSISTANT: Hello, what can I assist you with?

USER: I want to change my existing reservation due to bad weather condition, can you please help me with that?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: We have found reservation on your name, please share your updated airport codes.

USER: My source and destination airport codes are BOS and LGA.

ASSISTANT: May I know your travelling dates?

USER: I want to fly on Nov 18, return on Nov 20.

ASSISTANT: Do you have any other preferences to make your journey more comfortable?

USER: I want direct flight.

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no direct flight available at this moment.

USER: No problem, thank you.

ASSISTANT: Thank you.