You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Patricia Nelson.

ASSISTANT: How may I aid you Nelson?

USER: I want to go on a vacation to Houston.Can you help me to book a ticket from PHL to IAH?

ASSISTANT: Sure, I will help you. Could you please provide your preferable dates of travelling?

USER: I would like to fly on 04/13 and 04/15.

ASSISTANT: Ok, please wait a moment to check the flights.

USER: Sure, take your time.

ASSISTANT: Sorry to inform you that, there are no flights available in your locations with your requested dates of travelling.

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

ASSISTANT: Thank you for reaching us, have a great day.