Disappearing Data

I use to advocate for Telkom mobile as the cheapest mobile network. Now I see they have joined Vodacom and MTN in robbing us off our data. since I have a contract with the network my data disappears. I have a router which gives 5g during the day and 10g at night plus I get 1g on my mobile network. The data is depleted in two weeks regardless of the fact that I connect to my work Wifi during the day. In other words 6g is used between 6 pm to 9h30pm during the week and weekends. The only response I have received from the network is that the data is depleted by the mobile application. The more data I purchase the more is consumed. isn't the same amount suppose to be used monthly if it is indeed the applications. Then they send the useless data usage statement they cant even understand and doesn't give the sites that consume that much data.