You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am David Harris here, I want to reserve my ticket from CLT to PHL, can you please help me?

ASSISTANT: Sure, can you please share your travel dates?

USER: Sure, my preferable dates of journey is from 03/31 to 04/02.

ASSISTANT: Let me check for the availability of flight.

USER: Sure.

ASSISTANT: David, there is no flight available at your requested dates.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: You are welcome.