do they have a download limit ? NO, then tell them to pound sand.. you pay for cable service, you expect to be able to use it as much as you can. if that means you are download 24/7, then that's the way it is. they don't like it, let them drop you, which, if they don't have a download limit, would be hard for them to do.
I have cable internet, and I run my machine 24/7, and I download about 5-10gb a day, on a good day. then other days, I don't do anything.. but I would be very mad if my cable company called me about too much use of the service. I would tell them to stop calling me, because If I pay for 24/7 service, I will have the right to expect to use it. it's that simple.