Disgusting service from post office

I have an urgent parcel which was sent from pietermaritzburg to durban and its been sitting in durmail for the last two weeks. Ridiculous I have called often no response when I do get through they say they don't how long till it's delivered, I e-mail about 15 times only two responses they just say it's with durmail. I need this parcel for my work. Without I cannot work. Should I sue for loss of work.