You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Donald Allen here.

ASSISTANT: How can I assist you today?

USER: I would like to go Austin, so can you help me booking flight from IAD to AUS?

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

USER: My travel dates are 08/25 and 08/27.

ASSISTANT: Let me check for the availability of flight.

USER: Ok, I will wait for your reply.

ASSISTANT: Donald, I am sorry to inform you that there is no flight available at your requested dates.

USER: Oh! It's ok no problem, thank you for your services.

ASSISTANT: Thank you for contacting us.