Misleading of product

Almost 2 months ago I got a call from Telkom mobile to renew my contract and as I had such great service the previous 2years I agreed. I was offered a Sony M4 Aqua with 1GB and 100 minutes for R299 pm. I was informed that only after using additional calls or data usage would increase my bill amount. I even asked the sales person to confirm this about 2-3 times as I was told the call is recorded and legally binding . I have not used any additional data or calls. My first bill was R900 (I assumed due to pro-rata it was that much) but this month its over R600 this is not what I was promised or agreed to. I hardly get calls as almost all my calls go to voicemail. Please listen to the call before contacting me. This is misleading product and billing information and not what I agreed to! I want this fixed ASAP and will definitely be taking this further if not rectified as I cannot afford this . I am so disappointed by the bad service I'm getting now and regret renewing my contract!