You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I am Sandra Collins. I want to travel from IAD to LAX. Can you help me to book a flight ticket?

ASSISTANT: Sure, may I know your planned travel dates?

USER: I want to travel in the flight on 07/05 and 07/07.

ASSISTANT: Ok, please wait for a while.

USER: Ok, take your own time.

ASSISTANT: Thank you for waiting. Sorry to say, there are no flights available for your desired dates.

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

ASSISTANT: Thank you for reaching us.