BSNL COMBO PLAN 2841, 8MBPS FOR 175GB,BUT GETTING 4MBPS

Yesterday I had changed my plan from 999 to 2841, but did not change the speed, speed is still 4mbps.
I have contact to the exchange but they are saying the same speed you will get.
what to do..???

My line rate status.

Downstream Upstream
SNR Margin (0.1dB): 269 276
Attenuation (0.1dB): 250 165
Output Power (dBm): 19.5 12.5
Attainable Rate (Kbps): 21804 1248
Rate (Kbps): 8191 508
D (interleave depth): 64 1
Delay (msec): 14.68 1.13

Yes, I am also on that plan for the last few months (hell I am on it still but my road is dug up for repair and BSNL lines disconnected probably for a few weeks or more though I still have to pay for it) and I receive 4 Mbps highest. I suppose this situation is due to the lines being too old and not being able to hold a capacity of 8 Mbps.