You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: My name is Ruth Thompson. I have planned a trip with my ex-colleagues who are staying at Phoenix, can you help me to book a ticket from DFW to PHX.

ASSISTANT: Can I know your travelling dates?

USER: The travel dates are from 03/24 to 03/26.

ASSISTANT: Sorry, there is no flight available at your request.

USER: That's really sad. Thank you for your help.

ASSISTANT: You are welcome.