9 months and nothing

I purchased a Series 3 Tivo last Christmas for my family. I have cable service through Mediacom in Columbus, GA. Since initial setup I have been through 3 sets of cablecards and a second series 3 unit from Tivo and yet to get anything but basic cable stations. I have spent hours on the phone with both Tivo and Mediacom tech support with finger pointing in both directions. Tivo says the cards are not enabled. Mediacom says the box is not functioning properly. I have upper level support from both companies who are supposed to be working out the problem with each other but still nothing. Am i alone or is this common. Can I hook my series 3 to a cable box in any way like a series 2 and get the digital channel. I'm getting nuts. Any help would be appreciated.