You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Jack Nelson here. I want to change my reservation, due to some family reasons, can you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: I have found a reservation on your name, can you please share your airport codes?

USER: My respective codes from AZ- PHX to CA-SFO.

ASSISTANT: May I know your travelling dates please?

USER: Sure, I want to travel from 07/05 to 07/07.

ASSISTANT: Sorry, there is no flight available on your requested dates.

USER: Its ok. Thank you for your service.

ASSISTANT: You are welcome.