It took the University I shall be teaching at 24 hours to get a certificate from the bureau of foreign affairs in Zhejiang province. It was then faxed to me and I got my Z visa within a week at the Chinese consulate in Marseille. It cost me 35 euros and I could have had it within a few hours had I been willing to pay an extra 30 euros. I have however heard that with other bureaus it can take longer. Nevertheless don't go to China on another visa than a Z visa, just don't! whatever they say at the other end... If your university can't get you the necessary paperwork, that may mean that they are just simply not allowed to do so, then run away to another university which has all the authorizations.
Best of luck