mtnl delhi

HEY FRNDS THESE Days i m facing a strange problem I HAVE MTNL DELHI BROADBAND CONNECTION 599 MY OWN ROUTER D-LINK DSL 2520-U NOW THE PROBLEM IS THAT MY INTERNET CONNECTION IS FLUCTUATING CONTINUOUSLY FROM LAST 15 DAYS IT WILL REMAIN FOR MAX 15 MINUTES THEN FLUCTUATES CONTINUOSLY I...