Still receiving billing notifications after two techs determined that my address isn't servicable.

I signed up for Internet, TV, and Voice.  After receiving the equipment I had to request a tech to come and install the system because it didn't work with the AT&T wiring that I currently have.  Two different technichians came to my home and tried all of the coax outlets, searched the outside area for previous Comcast cables, and could not get the system hooked up.  The home is a townhouse complex and apparently because ours is a middle unit with no easily accessible crawlspace under the house there was no way to find the existing cable or install a new one.  It seems that the people who installed the AT&T service many years ago may have buried the old wire under the house, or something like that.  It was all a confusing explanation, but bottom line, the second tech who came said it just wasn't possible and that he would make a note that the address isn't servicable.  He took the equipment with him and I had to stick with the AT&T network.  Now I'm still receiving emails and letters about my first months bill, but I can't find anywhere on the website to reach somebody to explain this to.  Could somebody point me towards the right department's contact information so I can get this resolved?  I shouldn't owe any money whatsoever and I just need my account deleted.  Thank you.