Used this SIM for the past 6 months, this Sunday around 00:00 it died on me. Now am hesitant on buying the 1TB deal on the 25th.
As others have stated, a Cell C shop will sort it out.
Two & a half months ago I loaded a 100GB bundle (after converting R199 airtime on a phone), and the SIM died immediately (red light on router) ; thought I'd lost R199 outright. A Cell C outlet loaded the entire bundle to a new SIM, for a fee of R11 - was relieved though, that I'd not lost the R199 value / 100GB of data.