Vodacom WiFi unfare billing

I have a WiFi contract with vodacom and find that in less than 8 days all my data(10gigs)has run out.I contact the call centre and the consultant doesnt even take down my phone number and tells me to visit the neqrest vodacom store to check my cellphone settings.I have disputed the fact that I am being charged incorrectly and all I get is an email with itemized billing.It doesn't help the fact that for the rest of the month I cannot use the WiFi I paid for because I have no data.To top it all off I am told that I'm the one using the data but how do I know if their systems are faulty and are incorrectly charging me for data even when I am not connected to the WiFi.I have been a loyal customer for so many years now I'm thinking of changing my network.