Netplus Broadband — irritating to customer

Address:

Mohali, Punjab, 160055

I was using netplus broadband service last 5th months. I've used 3 months regularly after that i sent deactivation request due to some reason. But netplus send to me notice regarding outstanding bill and i already clear out all pending bills. But he is call me back daily ask for paying bill and irritating and also my connection was terminated. After terminated my connection i face some problem that i cann't complete my project.
What netplus responsible for this