Tracking of Shipments

I ordered products from a supplier. The package was send from Nederland NL The Tracking number is RS ********** 83NL. The package was scanned into JHB INT MAIL CENTRE (HUB) on 21 April 2018. Since the 15 May 2018 I tried to follow up as to when my product will be cleared at customs and delivered. I had no response to various emails sent to Customer Services, EMS and International queries. I called the following telephone numbers several times ( ********** 006/7/8/9/10/16 , ********** 000/1, ********** 1502) daily and the lines rings constantly with no one picking up the call. How is our national SAPO getting away with this. Nobody is responding and how does someone take a query further. The Track and Trace is not updated. How do we escalate the query?