FEDEX POOR SERVICE

We have a shipment that went to the state store. We did not receive any documentation or notification of the shipment. We only found out it arrived in SA when we tracked the shipment. We have paid the duties and asked them to release the shipment. they keep telling us that we must still pay R5000 then they are asking each other who must pay it?? We email and call but get no assistance. This shipment is critical to our business