DHL inefficiency and lack of customer service

Waybill No : *** This parcel was collected in Johannesburg, South Africa by DHL on the 27th October, to go to London, UK. It would appear it was stopped by customs somwhere around the 31st October at Heathrow, and then according to the Track and Trace website, was released by Customs on the 6th November. However, the parcel has never been delivered, the Track and Trace has never been updated since, and no-one from DHL is bothering to explain to me where my parcel is, or what has happened to it. I am not receiving any replies to my emails anymore, and am at my wits end as to what has happened to it. You would think they would at least have the courtesy to tell me that it has been lost if that is the case? This is appalling service from a major international company. The complete lack of interest and professionalism that they have shown is totally unacceptable.