The SA Post Office is unreliable!

I sent a fast mail 6 weeks ago from Merebank Post office in Durban to Pretoria, the people at the post office assured me it will arrive 3-4 days in Pretoria yet it is over 6 weeks and nothing! This is pathetic service at the South African post office especially when you pay for it! I want an answer as to how what happened to my mail! Are the people not doing their jobs!