Just requested Airtel to change my connection from Freedom 1699 plan (2 MBPS) to Turbo 75 (4 MBPS) after much deliberation. Will see how it goes, and if need be, will change to 150 GB plan. Was told that the pro rata basis billing has been discontinued and therefore all plan changes will take effect with start of new billing cycle only. Unfortunately, will have to wait another 10 days for the plan to take effect.