Hi, anyone can help with regards to application of business VISA in China?

Due to the upcoming golden week for China National Day holiday, the embassy in my country is also closed for 1 full week and I am unable to get my VISA in time before I travel.

No VISA is required if I travel/stay less than 15 days in China, but my business trip will be more than 3weeks, hence I definitely need a VISA.

Am I able to apply for a VISA in one of the Public Security Bureau (PSM) Exit and Entry Administration office in this case to cover my trip? What documents will be needed?

Thanks for any advise in advance.