UPS SA - Terrible Service & charges double without refund

Absolutely terribe service from UPS South Africa. They charged me twice for VAT and duties on a shipment and now it is impossible to get hold of them to get a refund. They do not respond to emails, the telephone number is either engaged, rings continuously or you're left on hold for 45 minutes with no one to help you. I was initally contacted by a gentleman by the name of Sibonelo who was quick to to take payment from me, but now a week later still has not responded to me with regards to my refund. I use DHL all the time and never have this problem. Do not UPS they are useless!