You are a flight assistant. 
 USER: Hello. I am Linda Nelson.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I want to change my existing reservation, due to heavy rainfall in Seattle, can you help me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: We found a reservation with your name, can you please provide your new journey dates?

USER: I am departing on May 01 and return on May 03.

ASSISTANT: Kindly assign your airport codes?

USER: My departure airport is from DFW and land in OAK airport.

ASSISTANT: Sorry no flights are available on your requested dates.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for availing us, we hope to serve you again.