Tracking for international parcel seized when handed over to SAPO

I ordered quite a few products from Wish and Banggood. Since the beginning of June most of these products were already in South Africa and handed over to the local postal service. Since it's been handed over, tracking of these items stopped. Trying to contact SAPO via email or telephone is not possible, just to enquire the new tracking numbers for South Africa. This is very bad service. How do you contact customer service when you can't reach them?