Overcharging Duty

Red flags on a Temu order at being charged nearly 50% of the order value on a smallish order. After persisting and finally getting a contact email, they confirmed what the duty was per item. What I was charged by Meile vs Sars duty fee was massively different. When queried Meili person acknowledged there appears to be an "IT problem." Considering no breakdown of cost is given when being charged duty this constitutes borderline theft/***** and should be looked in to