Yep. Apply online. It'll get changed in a day. selfcare.mtnl.in
Visit register.mtnl.net.in to check if plan has been changed.
Once plan has been changed, check line stats, if its 8mbit, cool, else call 12540 And ask them to increase line rate to 8mbps.
If they connection isn't stable, you'll have to go back to your 2mbps plan.