I agree, even I subscribed to Airtel VDSL 40 Mbps, which had intermittent disconnections. Tried a lot fixing it by calling customer support, technicians but to no avail. Finally, I had to apply for disconnection. They tried retaining me by giving me Bonus Data, but If I can't barely do anything on the Internet without getting interrupted, then what's the point of having the connection in the first place.
For the Bonus data, it is actually valid for 1 year, you can even get it renewed. I know, the guys who come to your place, they tell you it's valid for only 6 months but you can extend it to 1 year. All you need to do is to contact support. Furthermore, the backend people are more than willing to give you multiple buckets of Bonus data.