BSNL BROADBAND MODEM — Light blinks and connectivity goes off

I have DNA-A211-1 Broad band modem, installed at my residence. It sometimes works nicely. But for last few weeks the connectivity breaks after a few minutes and the indicator of DSL starts blinking. Then the entire system is to be turned off and restarted.
Modem has been inspected by Rajendra Nagar, Bareilly (UP) Exchange, but not giving sufficient relief. Surprisingly, one lineman, Mr. Ched Lal is on the helm of affair and BSNL Bareilly is not able to grant any relief.