Cellphone Account

At the end of November 2014 my cellphone contracts were upgraded. The consultant who did the upgrade never explained to me anything about package change or data usage. I was given paper to sign with regards to Insurance and new phones etc but that was it, not once was I advised about changes or amounts to this contract. In December I received a bill of R3500.00 which I paid, In January I received a bill of R6000.00 and another bill of R4000.00 for phones that are hardly being used. Last week I received a letter from Vodacom stating that this account was going to be given to collectors in the even of non payment. I do not even earn this amount! Secondly I have had consultants calling and harassing me for the money but not 1 consultant has called me to explain the escalated account despite me querying this account numerous times. My cellphone account has gone from R500.00 to R10000.00 in 2 months and I have no idea how or why. The service from Vodacom is pathetic and unexeptable.