It's been there for ages. They had the 15c per mb OOB back then then removed it then brought it back. Pretty decent price plan to be on. Add a whatsapp bundles to the mix and you already saving compared to other carriers.
One area that I got burned on this price plan was with 0800, 0860, 0861, 087 and a few other sneaky extensions, which are billed at R2.50 per minute on this calling plan.
Telkom Mobile's "Sim Sonke" plan may seem a little more expensive at first, but with far less fine-print regarding calls and data, it ended up saving me a ton of money compared with Cell C's 66c plan.
Adding to the above constant recharging gestapo attitude. You can have hundred Rands loaded and you will suddenly find that you cannot make a call in emergency. You can still receive calls, but your airtime is frozen till you recharge again. Ballance request return your correct airtime, but doesn't give information about expired recharge window, so you are fooled that you can make calls.
Something I have seen only with Cell C and is probably illegal.
SimSonke. Alternative MTN 1c per second price plan, no hassle assuming you are recharging with R30 or more. If you recharge smaller amount, read a fine print.
EDIT: There is no MTN 1c per second price plan anymore, so save your time.