DHL bad service

I ordered a product on Amazon on the 9th May 2019, selected and paid DHL express for shipment. The USA product arrived in South Africa on the 12th May 2019 but it was stopped at customs. I called DHL customer service on the 13th May 2019 after tracking the parcel online, to find out why it was stopped by customs and if there is a requirement from me in order to release the parcel. I was told there is no information why the parcel was stopped and they will let me know what is required from me. I called numerous times the DHL customer service between 13th May 2019 and 29th May 2019, I was told that they still don't know why the parcel has been stopped by customs. on the 6th June 2019 I receive a letter from DHL informing me that I must pay R1500 and get a letter of authority from SAHPRA for them to clear the parcel. I only received a bad service from DHL customer service department.