Data usage problem

My data according to Vodacom is being used even though 90% of the time I’m on WiFi. Called to complain again as this is not the first time and the lady was very arragant when I complained and asked for someone to get back to me by the next day. All she could do was make a note of my complaint and that it takes up to 3 day for a client to get a response. When I said that was not acceptable and she must please note that I want a response sooner, she very arragatly told me it takes 3 day and that’s basically it tone. If this is type of treatment I get from Vodacom, I’d rather move my business to another Cell company.