You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Kathleen Green here.

ASSISTANT: Hello Kathleen, how can I aid you?

USER: Yes, I need your help in booking a ticket, will you help me?

ASSISTANT: Sure, I will help you.

USER: I am planning a surprise to my mother on her birthday, which is in the last week of the month july.

ASSISTANT: That's really great to hear, may I know the location where your mother stays?

USER: Yes, my mother stays in Detroit, and airport code is DTW.

ASSISTANT: Ok, from where you want to start your journey?

USER: Yes, I would like start my journey from my current city San Francisco and my airport code is CA-SFO.

ASSISTANT: Well, would you please help me by providing your journey dates?

USER: I am planning this visit in the last week of July, It's from 07/28 to 07/30.

ASSISTANT: Ok, just wait for a while, I will check the availability and revert you as soon as possible.

USER: Sure.

ASSISTANT: Sorry for inconvenience, on your provided dates there is no flight available which is travelling to your destination.

USER: That's really sad to hear. Ok, I look for other alternative.

ASSISTANT: Ok, please look for it and make your mother's birthday as a memorable day to her.

USER: Anyway, thank you so much for your immediate response.

ASSISTANT: It's my pleasure.