Aramex threatening their customers with more charges

I used Aramex Global Shopper for a shipment from Singapore. It is 1 item, a pair of earphones. Total value is R360. Aramex told me that items under R500 does not carry customs duties. 2 weeks after my parcel is in the country Aramex tells me my package was stopped by customs and I need to submit a proof of payment to prove it is under R500. I promptly do this and Aramex now wants me to pay an additional R160 inspection charge. When I asked the agent why there are additional charges, he threatens me by saying if I "fail to comply" he will send my package to the states warehouse, where storage charges will apply. All of this for 1 pair of earphones, not even branded ones! Never use Aramex! They hit you with hidden fees, and if you query them, they threaten to load even more charges!