Webafrica mistake costing me money and they won't fix it.

I app**** for fibre months ago and it was finally installed. I then spoke to Webafrica about the process and they said that I must cancel my Telkom line as well and that it will take a few weeks. I did this immediately on the 30th of October. I just received an invoice for my Telkom line. I called them and they kept telling me that it is my fault because I didn't have my ADSL line cancelled with Webafrica. I kept telling them that I had but they didn't believe me and told me it is my fault. I then spoke to Webafrica who told me that they cancelled my ADSL line as soon as I upgraded to Fibre. They didn't do this and they didn't register it on my cancellation on their customer zone. After calling them they did it today. More than a month late. As a result of their stuff up, I am stuck paying my Telkom line for the next month or so. To quote them: "There is, unfortunately, nothing we can do about your Telkom bill" They *****ed up and now I have to pay for it and they don't even seem to care. I can't actually believe that they can make a mistake like this and make their customer pay for it. I don't think I have ever had such bad service in my life. "Nothing we can do" is a lie. They can do something about it and that is to pay for it. Then to make it worse, their customer service rep just stopped replying to me online.