VODACOM DATA USAGE

I took out a contract for my my mobile router to use at work only with Vodacom. The package was for 20G daytime and 20G nighttime data. Way above what I required. For nearly a year, my average usage was about 12G per month. However, during the last 2 or so months I have noticed a substantial increase in my usage although nothing has changed to warrant the increase. 6 call to them disputing the data usage and still have not even received a response from them. Having has contracts with them for over 20 years, I find this to be very poor service. Think twice before you use their service !!!!!