DHL incompetence

I have an instrument that was sent last August to USA for repair. It was repaired and sent back to me this August 4th It arrived in Jhb on 12th August for customs clearance. I received a request for proof of warranty and repair cost. The factory in USA provided the same even though this was part of the documentation they had. I heard nothing for 3 days. I called and discovered the email had gone to her junk mailbox. She found it and the next day i received another email requesting my ID. I heard nothing for another 3 days. I called again and found that the lady handling my package was not in today (Monday 17th Aug). i asked to speak to the manager and a supervisor called me. I explained the problem and she then sent another email requesting the actual warranty (which has no bearing on anything as the factory had stated clearly it was under warranty and i don't have warranty documents as the instrument is under lifetime warranty. She then asked for proof that it was sent from South Africa. This i submitted as DHL actually collected it from me (stupid). Now she tells me i will have to pay duties and fees on the item as it has taken more than 6 months to be returned. Who the hell set 6 months??? The factory was shut down for 6 months in USA but that doesn't seem to worry anyone. It has taken DHL several days and seeking documentation like the left hand doesn't know what the right hand is doing. I am really annoyed at the incompetence of DHL staff. first one thing, then another, then another, now a possible fee. I will NOT pay fees ir duties for something that is returned under warranty and left this country legally and also under proof of warranty. Such incompetence