Typically, MTNL plans are changed on the first of the month. Surprising that they changed yours mid-month. Anywaysm you have 2 options. First, control yourself till the beginning of next month before going all out. Second option is if you have the time and patience with the babus@MTNL. Use as if it is an unlimited plan, and If you get an inflated bill next month, take a printout of that email and go and meet the accounts guys or the DO. Tell them; if you are lucky, they will get some aunty to get a detailed printout of your usage and them you can crosscheck and get the problem resolved. However, the problem is that there is most often a discrepancy between the logs you see online and the printouts they give you. So, you will not have to pay for the entire bill, but yes, definitely for some of it. Best option for you is to wait till next month or at least for another 3-4 days before going berserk 🙂BTW, I have dealt with them for my NU problems a couple of years back, that is why I know about their logs/printouts