70% downtime with BSNL home 750 in Bangalore

We got BSNL broadband a few weeks ago (we live near electronics city in Bangalore). Right from the start we have faced 70% downtime. Here are some patterns.
--In the evening/night (from about 5pm -1AM), it is almost always down (95% downtime).
--During weekdays, it is up in the day (10AM - 4PM, 2AM - 3AM) almost always.
-- During the day, I get frequent disconnects (but it reconnects very quickly, but it is annoying as the IP address changes and I have to relogin to read emails).
--During the night, it disconnects very rarely.
--During the holidays (weekends, holidays), it is rarely up.


My modem is UTStarcom WA3002-G4, and I'm connected through ethernet LAN.
Any idea on how to solve this, or what might be causing it ?

A written complaint to the nodal officer and appellate authority may help. Address and phone no on the back side of your bill.