Hathway - Stopped my internet service

I paid Hathway an amount to stop my internet connection for a month when I was out of town. They informed me the internet will start automatically on the date I mentioned I will be back. After returning the internet did not start and In fact, they charged me for the month as well (in addition to what I paid to pause the connection). After going to their office for * days they finally started my connection. Since that though, every month I get an extra bill of **** Rs as a non-payment. They said it will be resolved in a month. It's * months it is still not resolved and now they have stopped my internet again from * days due to the same issue. They will charge me the total amount still in the next bill and not on a pro-rata basis. How can I go ahead against this?