Penalty fees after paying customs

I've had the worst experience with this company, everytime I order from Shein and Imile is delivery i want to wait for a long period , but recently I have had it , I made an order with Shein and few days after I receive the link to pay customs which I did immediately. Right after I made the payment i received an email stating that I should pay a penalty fee as Shein advised them on the wrong amounts and they have different categories and demanded i should send them a screenshot of the amount my order was These people basically wanted to charge me more than what my order even cost and this is after I already paid customs of R473 and then they cannot give me a proper explanation even saying that they understand it's not my fault but if I do not pay they will just send it back to the government and my package will be abandoned

I mean why is Shein even still using this company what a ******* to charge people so much for customs and still expect ranging from R500 to a R1000 no way