Airtel
Not getting network connection

Before 3 months i have taken Airtel internet connection. This connection is one year plan, because of that i have paid full amount for one year. But i am not getting net properly. For first two weeks i was getting satisfactorily. But after that i am not at all getting. Many times i have complained to the authorities. But they are not taking any action. So to whom i have to contact. Please tell any solution