Overcharged R1,155.93 just for 600g item shipment (CN to ZA)

I bought a phone from Doogee Global Online Store via Aliexpress.

The Item cost and shipment is as follows: Product Amount = US $ 232.94, Shipping Cost = US $ 41.04 Total Amount = US $ 271.98

DHL Tracking number: ********** 621 Package Size : 20cm x 15cm x 12cm Package Weight : 600 g Destination address : Technikon Laboratories, 1073 Anvil Rd, Robertville, Randburg, Gauteng, South Africa, 1709

After receiving this tracking number, the seller came back and advise me that DHL wants additional US $40 because the destination (shipping address above) is romote place.

Additional US $40 means I will now pay, just for 600g shippment from China to Randburg, South Africa, a total of US $81.04 (ZAR 1,155.93).

Why is this shipment so expensive? How is Randburg a remote area because Randburg is categorized as "central", never a remove area?

My parcel now is stuck in China because, in addition to the initial US $ 41.04 (ZAR 582.60) initially charged for shipment, now I am charged unjustified US $40 (ZAR 567.83)

Please clarify because Randburg is not a remote place, but in the heart of Johannesburg, Gauteng Province, and generally, shipment to this part of the world normally cost around US $40, never any close to US $80, and I always use DHL.