Indian ISPs found a curious way of tackling these situations. Since they sell their plans as unlimited, they can't fully cut off the internet access. So as soon as the fair use limit is crossed, the speed drops to punishing 256kbps till the month gets over :|.
256kbps isn't as terrible as it may seem. My internet used to be cut to 56k when it went over, and 95% of websites wouldn't even finish loading. Now I think it cuts back to 512kbps, so things at least load, just no downloading really.
Conmcast should do this. Not cut off his service, but drop his speed to 1MB/s for 1 month. He will then be motivated to find the source of the problem.
