MTNL Delhi — Frequent disconnection of internet

Address:

New Delhi, Delhi, 110040

MY phone no. is 27783010.I have a night plan i.e. during day i should got 60 kbps speed and while at night speed should be around 200kbps. The problem is since day one my modem Adsl power is unstable it took them 6 months to resolve that problem after that somehow it get pretty stable that means now it gets unstable every half an hour or an hour. Not only this after 5:30pm speed is gone totally till 10:00pm. It is very annoying because download often gets failed due to these frequent disconnection.It is almost a year and not even a single month goes when i do not enter a complaint.
It is my request to please solve my problem permanently. Or else i will not hesitate to go to consumer court.