I'm convinced that most SA country's taxes are double collected when travelling on a OWE ticket. If the taxes are not broken down on the ticket coupon, you pay again, regardless of what other documentation you have. LA in Chile is the shining example of this. Only once did I manage to get the agent to accept the tax breakdown typed on the back of the last page of the ticket package -- and that was in IPC after a lot of "talking" in Spanglish!