cannot cancel AT&T dishnetwork

In april I called AT&T to move my phone service to a new address I moved to. At the same time I canceled the dishnetwork service. They told me, that I would have to pay some cancelation fee and that they would pick up the satellite tuner. AT&T kept billing me for dishnetwork. So I called them again and I was told again the same thing. This repeated for another month and I called them again. In July I finally wrote them a letter and AT&T finally reimbursed me for these charges. Now end of July I got a bill directly from dishnetwork. Currently I only send them an email explaining myself and that I don't have any bussiness with dishnetwork.