Incompetence on paying attention to clients request - Randfontein Branch

On Monday the 5th of July 2021 I wanted to courier my goods to Middelburg Mpumalanga and I mentioned to the assistant its supposed to be delivered in Mpumalanga. The assistant told me that the postal code of 1096 does not exist on the system then selected a postal code without notifying me what the system had available on the system. I am now seeing on the tracking system that my package is in Middelburg in Port Elizabeth. How do I manage such incompetence from Postnet Randfontein staff. I will be heading to the Randfontein branch to request a clear understanding of such nonsense. I highly disappointed. Because I paid alot of mone y for this courier service