Matt,
Is Dadar area covered? As much as I love MTNL, I will part with them if you are giving 4 mbps unlimited plans. :ashamed:
If your usage is around 200 GB, then you can have 5 mbps flat-rate(fixed bill irrespective of usage) at Rs 1999 inclusive of tax.
At the same amount, you can have 145 GB (however with a hard cap) at 100 mbps. (or 150 mbps if your card supports it)