SA Post Office
Collection of material, but told its not there

I was Called in two times to collect my unisa study material. And they showed the date to collect; I've went there 3 times. And there is always one answer that they have not arrived. Firstly you give them a reference number. And they say they on strike. You give them a letter ordering you 2 collect your things before a certain date. But they just say its not there. But I have a request letter to come on this day. They lazy incompetent and have no clue what customer service is.