We have 2 separate tickets London/Shanghai Shanghai/Sydney but will be there 80 hours?

Hi My husband and I are returning from London to Shanghai (on Australian passports) and then Shanghai to Sydney.
We will be in Shanghai 80 hours from arriving at 7.55am and departing 3 days later at 7.55pm. How do we get a visa? We will be staying at a hotel and don't know anyone in Shanghai?
Regards

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