Deduction of main account balance while surfing

I have been charged every month from my main account balance when I am having the net balance. This is the worst thing happening to me evry month.I want my money Back from last 6 months or more than that. What is happening to Vodafone net series.Evrymonth my money is getting deducted from my main account and it’s not a fixed amount. Sometimes it’s Rs 75/-, sometimes Rs 50/- or Rs30/-.