Requested 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 top up which he advice me 2 call 808. The next day I called MTN and I didn't get through coz the MTN employers were on strike and I tried 2 call 4 2 weeks but I ddnt get through. Time had passed and 4 the past months I thout my contr was a top up until I received a bill of R2300 and my head spined coz I have never in my life had spend so much on my cellphone contr, i had my contr 4 the past 6 year which It was top up from the beginning cause I couldn't afford an open line. Im so disappointed with MTN becoz 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 to contact the sells department so they assist coz I upgraded wit them,I was transferred and spoke 2 a lady and she said that I need 2 speak 2 the consultant who has assist me and that time the consultant was busy so I cudnt speak to him and she said dat he will call me bck and I left my numbers but even today I'm waiting 2 be called. To be honest I can't afford the bill