BSNL Broadband
Getting very low speed on broadband connection

I have a BSNL Broadband connection with a 1 Mbps unlimited plan. Only a few days I got good (150-200kbps) download speed and after that, the download speeds are pathetic (15-20kbps). Can't even check mails properly.

I made a lot of complaints and was promised that it would be rectified. But nothing has happened.