DHL ****med me twice

Dhl is ****. A few months back I received an email from DHL to pay custom duties for a parcel. I paid the amount and never received anything. When I called to query where the parcel was they tell me that it was never handed over to them. My question was how do make me pay for something u have not received and how to you determine the amount I need to pay when u don't have the parcel. Fine I let that go. Monday I ordered skin products from the UK and unfortunately for me they used DHL *sigh. Boom today I received an email from DHL saying I need to pay R620 customs for a parcel that cost me R840. How ridiculous is that. When I call them they tell me about all these cost that have nothing to do with me. DHL ****s people of they hard earned money. They need to stop this nonsense of guessing custom amounts. I paid R1500 for a bag and got charged R350 and not I paid R840 for skin products and they charging R620. I will be posting on all my social media till they do the right thing. U can't **** me twice, I refuse