Can I change Business visa to tourist, then after that apply for extension of tourist visa again?

Dear Sir /Madame

I have been accepted to work for a University in China, I live in China. Iam English and hold a British passport. Iam currently on a Bussiness Visa which expires on the 14th of August I need to extend in order to leave the country and get a working Visa to work for the University. The University cannot supply me with all the documents the police station requires as the important leaders who can authorize the document are away on holiday. What option is left for me now to recieve an extension and obtain the working visa. Can I change the Business visa to a tourist Visa and if so, can I then get another extension on the tourist Visa as the University tell me it will take about two months to process the working visa. Thank you very much I realy want to stay in China and work could you please send me advice much appreciated.

Rafal Szczesny