How safe is mailing service? How fast is urgent processing?

The Hebei University in China has invited me to be with them for knowledge exchange. I will go there from December 10th to 26th. I am residing in Dunedin. Due to work, i cannot stay long in Christchurch to wait for 4 days. I am considering mailing service. However, i do not feel safe. I hold Malaysian passport. I had once lost my passport and had been through years of confinement by the Government of Malaysia.
If i go to Christchurch in person and request for urgent processing, can i had my visa in the same day? How much fee should i pay? I have not purchase my ticket yet. Can i ask for urgent processing? Thank you