Airtel — network issues in the router

Address: Mumbai City, Maharashtra, 400002

Almost every third day the internet connection is lost on my airtel broadband router. This is a serious problem as i use it got office and not home. I don't receive the physical copy of bill and then there are late bill payment charges added to the same how do i pay the bill without receiving it
Let me know what can be done or else i'll have to switch the network