UPS cannot provide a reason for delayed delivery

I had a parcel shipped with UPS on the 13th December, it reached South Africa on the 16th December and has been stuck at the airport since, the parcel was supposed to have been delivered on the 18th, so far I have not received any reason as to why it has not left Johannesburg but have been told that it is not stuck at customs and everything is fine with the parcel. This delay is costing me money.