I've been getting calls from Airtel since the beginning of September about migrating from 16mbps to 40mbps. But, it hasn't happened yet. And yes, I'll have to pay Rs. 1000 in 5 installments for the modem, if and when it's installed.
After waiting all this time, I wrote to 121 yesterday. In response, someone called me and said that there are some issues which will be resolved within 72 hours.
This morning, I got an e-mail saying "my top up (broadband surprises)" will be deactivated from the next billing cycle. I'm hoping they're preparing for said migration.