Appalling service

I placed and paid my first order just fine... The order amount was R1359, and I paid Buffalo R121 thereabout.. Everything went well I must say.. I received the order in time and in good condition.. I then placed another one on the 30th Oct.. Up to now I still haven't received my order.. When I called Aramex I was told that my order is been held and Customs and normally it takes about a week to be cleared... Up to now I have received my order.. The other pecu**** thing is the first order was R1359 I paid R121 shipping costs.. Now this time my order is R3651 and shipping cost are R1000.00.. How exactly do they calculate the costs... Also on their page is says spend R2960, and be eligible for free shipping cost... So now how am I paying R1000.00 when I spent R3561.. Or maybe I am ready it wrong... I am seriously not happy with Shein at the moment.. To think I wanted to buy Christmas things from them... Maybe I was only going to get them in April awaiting customs clearance