Australia to Shanghai to London

I have a booking to fly from Australia to Shanghai (PVG) and will transit through Hong Kong Airport on the same ticket. I then have a separate booking from Shanghai (PVG) to London (direct) just under 48 hours later. Is this eligible for the 73 or 144 hours Visa?

Also, my flights from Australia are Qantas to Hong Kong and then Cathay Dragon to Shanghai (all same ticket and remain airside). Do I lodge my request with Qantas before boarding in Australia or with Cathay Dragon in Hong Kong?