Courier costs almost the same as the value of the order

I bought 3 pairs of shoes for my sons (they have size 13 and 15 feet so I usually order online as this size isn't available in shops). The value was ZAR7500. Footlocker do say we must settle the customs duty but the bill arrived today with the parcel and it is ZAR3978.94!! I could refuse the package but then I get no shoes and it's cost my ZAR7500. The courier is under no obligation to return the goods. Or I can pay the R4000 and then return the shoes and get my R7500 back. Either was as the consumer, I'm *****ed. I will NEVER buy from Footlocker again. The only recourse is to pay the clearance but I will also be querying the bill with SA Post Office.