I called Vanguard again and asked for a customer service supervisor. This time I got someone with some sense.
She went over the invoice with me point by point, explained everything, and said the shipper in South Africa should have told the mine about these charges so they could tell me. So it sounds like that's who dropped the ball.
I have so say, I do like the mine staff. They have been very helpful throughout this process.
In any case, the shipment was released today. The container has been picked up and will be stripped (unpacked) tomorrow.
And the rocks should be on the way by Friday.