I don't use it but I did call in and they sent me the details.
They give you an account with reference to put the money in starting with R1000 ex vat so R1150. And each time you use the service the money gets deducted from that amount. The balance must not drop below R100 and subsequent deposits of R1150 has to be made.
There is two types of accounts the "one rate national" and another one "online 2" I think. Under certain circumstances the one rate account will be cheaper than the online 2 like for larger packages.
But for smaller packages it's not so cheap, one rate has a minimum charge of R110 for a overnight package up to 2kg and R38 per kg thereafter and on the online 2 package the minimum charge is R80 up to 2kg with R35 extra per kilo and the caveat of a R60 a "regional (outlying)" surcharge.
You have to choose one account which complicates matters if you have packages of varying sizes and weights.
I found their whole pricing structure a tad confusing because they have these two different accounts with different prices, then there is the local pricing, national overnight courier, domestic airfreight and the national road freight pricing each with multiple tiers for distance/time/weight. But after spending some time reading it I got a better picture.
They also send you a 8 page document to fill in including a "bond of surety" which I found strange for a prepaid account. They do have some crazy surcharges like R455 for "chainstore, embassy, government departments" which I found excessive. So if you have R1150 in your account and send ten R110 packages to those places you can end up with a bill of R4500. So maybe that's why they want you to sign surety.
Honestly, I wasn't too impressed by their pricing (the online 2 prices is vat exclusive according to forms) I thought they are much cheaper considering how popular they are, maybe credit accounts are cheaper especially if you doing higher volumes.