Talking with a real human at Comcast won't help in this case. You have to talk to a specific department, not just a regular service rep who can do absolutely nothing for you. Neither can the specific department, but that's a whole 'nother story.
Believe me, I went round and round on this one a few years ago. They cut me off because I goofed and sent a mass email to our OPT-IN mailing list a few hours too early. It was on the eve of an important local election and the emails were our last attempts to get the school supporters out to the polls. Made me madder than spit, needless to say. The first time it happened, I'd been completely unaware that there WAS an upper limit on the total number of outgoing emails allowed in 24 hours; it's not something they go out of their way to publicize. Needless to say, I was already aware of the limits on the number of recipients at any one time (though if you ASK the reps, that's a moving target too) and had a script to split recipients. All in all, Comcast goes out of their way to prevent spammers from using their system, but does nothing at all to help those who make legitimate use of the email system or to differentiate between the two.