DHL are are a buntch of incompetint people

HI have a package from China that I am waiting for that was supposed to be with me on Wednesday 05-08-2015 however my parcel was in JHB last week Friday, so on Monday I tracked the parcel and found that it is still in JHB I contacted them and asked the why my parcel is still there and they said that no it is being retained by customs I have to pay 10% tax, however no one contacts me to tell me that my parcel is being retained. so I pay the money then send proof and still I waited now my parcel is being retained again for inspection and I need to send them the proof of payment of the product not that tax. why must I do this? as the invoice is with the product if they did not have it how did they then tax me??? also now I have to provide them with SABS documents this is not my responsibility this is DHL they must provide all the documents that they receive from the supplier now I must do there work for them. I don't have what they need they should have been issued with this when the parcel was collected as that is SOP, now I have lost sales as my parcel has not arrived and my customers said that my service is bad. also keep in mind that i paid around R3000 for excluding tax