Being ********** monthly for "DATA" usage!

This is day light ******* on the 30/09/2017 at 16:16 P.M I received an sms to advise that I have used R11 out of data bundle , All of a sudden I get charged R 63.18. I have UNCAPPED wifi at home and there was no need to use your data as I was at home the weekend. This is not the first time this is happening. I cannot wait for this contract to end I have been with your company for approximately 20 years, 20 years too long and 20 years of pay exorbitant prices and being over charged. I still have the sms sent to me !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I need an an explanation TODAY!!!!!!! Its not the amount as it might seem insignificant it’s the PRINCIPAL.