Wrong charges

I've just app**** for eskoms 3 phase power for my bussiness of which they came and connect. But to my surprise they started charging before I even started connecting my machines and I'm forced to pay R4400. 00. When I enquire about this, they told me they've just estimated that amount. And they are forcing me to pay. Can you pls help me with this issue. Your will be highly appreciated. Thank you