The offered speed is in between ISP's server and your home. not from any destination to you.
In case you are using MTNL broadband, the speed also depends of the distance and condition of copper cable you have from your exchange (ISP) and your home.
suppose i am close by within1 or 1.25 Km distance. i have up to 2Mbps speed. i actually get 1780Kbps approx. it changes from busy hour to lightly loaded slack hour.
but it sounds 50Kbps (or is it 50KBps kilo bytes) appears horribly low. Even on a dial-up would get 56Kbps. please upload what exactly you get like kB or Kb the difference as you know is KB=8*Kb
perhaps, if the distance is more, and line little noisy, -check the SNR and attenuation figures, you might configure D.GMT mode instead of ADSL2+ or some such, you might get improvement.