since they are a utility, they can charge all they want as long as they don't discriminate, they can decide to charge all data at 1000Rs/MB. Even a 1800 kind of service is also ok, wherein service provider will pay for the data and not end user, as long as any business can join in.

Now the question is why should some business be treated as utility, it is because they control access to limited natural resource, which somewhat prevents free competition