They called me from what I guess is the main office (guessing from the area code) and apologized profusely, and the person calling swore to me she would personally handle a cable modem install, and give me three months free service. She couldn't be more apologetic and says she is going to foward the letter to engineering, too.
I did explain that I think I have a contract with Earthlink, but she says the offer stands for as long as my contract may be, to keep her direct line, if I ever want to go ahead with the cable modem.
I have some thinking to do. But they did follow up, it didn't go into a void.