Pay for a service which I did not get

I opened an account with VOX, which did not work, and when I phoned to get support I was told I don't have an account with them, so I got an account with Axxess instead. By month end I got a message saying they were gonna take money from me, and when i phoned to cancel was told I need to give 30 days noticed. I then spoke to someone at accounts and explained the situation, and after a heated conversation was told that the problem was solved. Now months later I get phoned by a debt collection agency to make payments. I need someone from vox to phone me so we can sort this out.