You are a flight assistant. 
 USER: Hello. Debra Lee here.

ASSISTANT: Hello, what help do you need from us?

USER: I was looking for a flight on the route from Washington IAD to San Francisco SFO for meeting my sister, can you help me?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Can you please mention your planned travel  dates?

USER: I will be travelling from 07/27, I want return back on 07/29.

ASSISTANT: Ok, please hold on for a moment.

USER: Take your own time.

ASSISTANT: Sorry to tell you, there are no flights found in this route.

USER: Ok, thank you for assisting me.

ASSISTANT: Thank you for consulting us.

USER: You are most welcome.