MTNL Triband — Low Speed

Address:

Mumbai City, Maharashtra

Dear sir,
i want to complaint about my low net speed. when i brought my mtnl triband 1Mbps unlimited plan they claimed me 256 kbps download speed, and i used to get it, but after 2-3 months speed started decreasing and now am getting 70-100 kbps download speed. I complaint thousands of times to 1504 and 198 also but no one is bothered. please do something, or else i need to change my service provider.
My land-line No. is [protected]