Refuse return and do not pay promised partial refund

I recently received a Facebook ad about this organisation and their offerings. Their website looked legit as they have a 30 day refund policy. I placed an order online and received the product. They advertise being South African based. Two items are shown on your adverts and even the order and the receipt – which leads one to believe that two items are 1 x Unit. I was seriously overcharged for 1 x Unit consisting out of 1 x item (not two as advertised) that comes from China, not South Africa. The exact same item can be bought for 1/3 of the price directly from Temu or Shein. When I complained about this, they offered me a 30% refund and did not want me to return the product. It has been 4 months since, with me following up twice a month, and no refund has been made. SERIOUS DODGE - stay away