R1900 Roaming charges, Never left SA!!!!

My account has always been close to R2000/mth, and I always accepted it as usual. I then had wifi installed at home and started using wifi at work and everywhere it was available to me. Still my account reflected me using R2000 worth of data, some times R800/day... I requested a investigation into the charges and they came back informing me that there is absolutely nothing wrong with the charges and that that is the data I have been using... I then changed my contract to a Uchoose SmartS and Vodacom informed assured and guaranteed me that it is impossible to exceed the contract fees and that once my data or airtime has been depleted I would have to buy Data and airtime, and for the past 2/3 months I have been purchasing data and airtime via my FNB account. Still I have been paying R2000/mnth and currently my Vodacom bill is R1900?????? I just got off the phone with Zakele from Vodacom and now all of a sudden it is not Data charges but ROAMING charges????? How is it possible to have R2000 roaming charges if I have not been out of the country??? This obviously means that Vodacom have been Loading roaming Charges on my account for the past 2 years, can anyone HELP me please?!