I'm an Australian, will transit Shanghai for about 70 hours, I can't get a visa in advance, can I apply a visa in Shanghai?

I have an Australian passport and am visiting the UK. I am returning to Australia via Shanghai and Vietnam. There is a 70 hour gap between my arrival in Shanghai (7/19) and departure to Hanoi (7/21). I have been unable to get a Chinese visa due to misinformation. Could you advise if there is any extension to the 48 hour visa exemption? Or a visa I can apply for in Shanghai?