Request not fulfilled/ Breach of contract

In April 2015 I upgraded my MTN contr and my sales consultant was Christopher which he was a great help,Before I ended my call I requested the consultant 2 put my contr as a topup which he advice me to call 808. De next day I called MTN and I didn't get through coz the MTN employees were on strike and I tried to call 4 weeks but I didn't get through. Time had passed and 4 the past months I thout my contr was a topup until I received a bill of R2300 and my head spined coz have never in my life had spend so much on my cellphone contr, I had this contr the past 6 year which I had it as a topup from the beginning cause I cudnt afford an open line. Im so disappointed with MTN because my requested hadn't been fulfilled. Last week I called MTN direct to correct the bill and I was advice that they cant do anything and I need 2 contact the sells departm coz I took de contr wit dem which I was transferred 2 sells and spoke to a lady and she said that I need 2 speak 2 the person who assist me and at dat time the consultant was busy so I cudnt speak 2 him and she said that he will ask him 2 call me bck n Ileft my numbers but even today I'm still waiting to be called. Honestly I won't afford