Extreme over charging for Data

My mother has been tortured by Vodacom for months now trying to resolve this query after receiving a R12,800 bill in July 2014, while her average phone bill was R1,200 previously. After stopping the debit order and complaining to Vodacom they continue to say they will not do anything until the outstanding amount is paid. My mother is unable to pay a bill of this magnitude yet Vodacom continues to deliver the worst possible service which has brought her to tears on numerous occasions while sitting in the Vodacom branch for hours with no resolve after months. Vodacom still has audacity to charge us for the Mins, SMSs and Data which we cannot use because they have deactivated our sim cards, while charging interest on the erroneous amount. My mother continues to pay the minimum monthly costs for our contracts plus extra which has amounted to R6,100 over the last 3 months yet we can't make calls for the past 3 months and we have been unable to receive calls for the last 2 month. This is unacceptable and extremely incontinent. I wish I could put a banner up in front of a mall and highlight how *********** Vodacom is. Complaint Ref Nr S3-1TH2C-C****