Parcel disappeared in 3 days

I received a notice stamped with a stamped date of 17th January 2018 that I have a parcel at Mamelodi West post office on the 19th January 2018 and I was told that the parcel was not there then the lady decided to ask if I had already collected the parcel I would not have the slip if I had picked it up. This is not the first time this has happened at the same branch, a previous occurrence was the 1st of December. So what I would like to know is what happens to our parcels? Because even the head office keeps making empty promises.