Frustratingly poor service

This company has the worst service ever. I canceled my contract with them mid November which they told me would be canceled end of December due to their full calendar month cancelation policy, that's fine. They on the 3rd of January they still haven't canceled my contract which means that my new ISP can't come connect me as the line is not released. I phoned them on the 3rd and waited for 40 minutes to speak to their consultant who told me they'll release the line and am still waiting. These are the things that annoy me with this company. I canceled my contract because I've been struggling with their unstable connect for a very long time with no solution and now they are not releasing my line. I don't know what to do with this company. Poor product and worst service ever