Unable to cancel Cell C Got It

I cancelled the subscription to Cell C Got it last year Nov 2015. I called them and they confirmed that the service had indeed been cancelled. Today I get my bill for Jan and Feb 2016, and see that I have yet AGAIN been charged for the service that I cancelled last year. I have now tried to phone the Got It department and have now been hanging on the line for about 20 minutes without getting access to an agent. This is REALLY BAD service. What must I do to get this service cancelled once and for all, while also getting my refund for Jan and Feb 2016 ? It actually is a pity, because the service I have gotten from Cell C itself has been great.