BAD SERVICE

I sent a parcel to postnet sunnyside on the 18 september and paid R185 for overnight delivery, now its the 20 of september and my parcel has not yet arrived. when i go there to enquire its only then that they said the parcel to hamanskraal takes 3/4 working days , but then the 3/4 working days price is charged 100 not 185. so they ****** me,