@ abhishek ... u r right. since the distance from exchange is greater, they will provide extra line and use a line bonding modem to give u 8mbps. u will need to go personally and talk to them.
i have a 150gb limit on vdsl and inspite of downloading tons of stuff i don't breach it. Higher speeds do not equal higher quantity of downloads.
Even with 100mbits at my disposal i barely managed around 150gb a month.