Incorrectly charged for custom duty and poor services on dealing with refund

I had been waiting more than 3 weeks after submitting my refund claim form, and no email reply or telephonic notification about the outcome. Been tried to find out the status via email and never got any reply. Very disappointed that SA post office and the custom in JHB International Mail Centre. All I want is to refund me the money I overpaid for the custom duty and vat. The parcel was valued HKD 200, not USD 200!!!!! Why asked us to email to complaints but never reply the complaints?????