Data usage billing dispute

I received an sms from Vodacom on 4 November 2015 stating that my sim card is softlocked as I owe an amount of R 1990 for the month of October 2015 & R323 from 1- 4 November 2015.i requested for the itemised billing for the months of October 2015 &Novemeber 2015.Upon inspecting it I realised that about R1600&R 300 was only for data usage for the months of October 2015&November 2015 for data which I did not use as the data was used either while I was asleep or in meetings at work.I always switch off my data when not in use & have set applications to update only when Wi-Fi is on. My sim card was locked on 11 Novemeber 2015. I could only receive calls.I did not get any joy from Vodacom when i logged a dispute with them. I then reported ths matter on ths website. The invoice for October 2015 was revised to R444 instead of R1900.I was told to wait till 2 December 2015 for another call to be logged withvtge data department.The call was eventually loggef by a store manager in Pretoria on 9 December. On 14 Decemeber 2015 i was told that tge matter has been referred to the data department.The matter has still not been resolved dispute the fact that I reported it on 5 November.Please assist