Please tell me the address in Beijing, from where I can buy the China Southern Airlines Tickets: from Beijing to Islamabad, Pakistan. I know that this flight CZ795 is operated by PIA as code share flight.

I want to ask further that same flight PK 853, every Monday, goes from Beijing to Islamabad and then Lahore, Pakistan.
But i can see on internet that only up to Islamabad this flight CZ795 is available. Can I get ticket from China Southern Airlines from Beijing to Lahore? I want to go to Lahore with my family in Sep 2010. Please guide me.