Is Telkom *****ing or unable to do Math or what is the problem

In light of the VAT increase I notice that my billing amount is higher than it should be if only the VAT was increased.

if 549 ZAR is the base amount plus 14 % VAT then 503.38 ZAR is the base amount plus 15% VAT and not 505 ZAR - so the question is why the extra 1.62 ZAR - The lady in the Telkom chat really tried her best but does not have any other authrity then myself. So perhaps there is somebody at Telkom who can explain the bill to me