never missed a payment, but no service for months

In October 2013 my cellphone contract with cell c was upgraded and with great anticipation I got a new phone. Unfortunately my excitement was Short lived, after a fewweeks my new phones internet stopped working, after countless phone calls to cell c call centers and jotting down many reference numbers, I realized I will never get internet from cell c and I will have to pay for it each month. I accepted defeat and bought an MTN wireless router which works like a jet! A few weeks ago my cell c phone started having intermittent signal, signal would be gone for a few days at a time, I tried the call center thing again, but not nothing has changed since 2013. I borrowed a MTN Sim card for my phone and I had perfect signal and 3G internet for days! Put back the cell c Sim card and back to the intermittent signal with absolutely no chance of intentet! How could cell c bind me in contract, take my money and not provide the service the promised? I need help to get back what I lost, what I'm still losing!