Registered letter stuck at Witspos hub

We sent a registered letter from Johannesburg to Pretoria on 10 May 2018. Two weeks later it has not arrived, and after contacting the Post Office to do a tracking, we are advised that the letter is somewhere at Witspos Hub, and that if we want it urgently (which we do) we need to go to Witspos Hub and hope that they can find it for us.

What is the point of posting by registered post if we have to waste time and petrol driving to Witspos Hub to collect our post? I am not very confident that we will be able to find the letter at Witspos Hub, given the delay.