Appalling service from DHL - use another shipper

My package arrived on 7 May 2019 from Hong Kong at Jhb Int Customs and was scheduled to be delivered on 10 May 2019. On 14 May I phoned DHL and was told that it was stopped by customs. After numerous calls on 29 May I was told that DHL used the wrong tariff code and I was invoiced to pay the extra duty and vat, which I did promptly. From then to now (10 June) I make a daily call to DHL and nobody is helpful and neither do they return my calls. I have sent an email and had no response. DHL advertises " send a complaint straight to the top - Jed Michaeltos country manager" - I phoned and left a message and again no response. It is clear that the DHL staff are very ***********.