FedEx imports department don't know how to calculate VAT

I was supposed to receive my package from China on the 1st September via Fedex. Shannen contacted me to request proof of payment for my package. I sent her my credit card statement confirming the transaction i made to the supplier. The value of the items was $94. Fedex imports department also requested copy of invoice from my supplier which the supplier provided. Fedex later issued an invoice with incorrect customs value despite supp**** proof of payment and invoice. They calculated custom duties based on R4600 which was incorrect because i had paid R1321 for the order which was even visible on my credit card statement and also the invoice. I have been calling Fedex everyday for the past 3 weeks to get them to invoice me correctly so that i can get my package. Today i received with shock what was supposed to be a corrected invoice only to learn that Fedex does not know how to calculate VAT. The same VAT amount of R837 which was used on the previous invoice was still the VAT amount for the new value. How on earth does R4600 and R1300 have the same VAT amount. How unprofessional of Fedex to fail to work out such a small query. It has been 3 weeks now and i need my package. Fedex is used to ******** people in the name of customs. Fedex i want my parcel. Issue me a correct invoice and give me my package.