He's incorrect.
Duties and taxes are easily looked up.
Every product has an HS code (Harmonized Standardization Code), which states the duties and taxes for that item.
HS Code for mobile phones is 8517.12.906
There is no duty payable on Mobile Phones, just Tax @ 14%
SARS document here:
http://www.sars.gov.za/AllDocs/Lega...4 - Schedule No 1 Part 1 Chapters 1 to 99.pdf
His shipper may be arbitrarily adding fee's and what not, but customs will not charge random fee's unless the goods aren't brought in under the right classification code (in this case 8517.12.906)
You likely will however have issues with ICASA, as all radio devices require ICASA type certification, so if you buy a phone that isn't sold here, and doesn't have type certification, they may impound it until you pay for type certification testing.