Trying to terminate the services

On moving I phoned the Telkom offices to terminate the service, namely the 29th December, 2015. They told me to communicate with my ISP to bring this to an ordinary voice line. This was duly done, and the line was changed. The e mail from said company is on file. I moved on the 29th December, 2015 and gave the owner the keys to the flat. I no longer have access to the building yet alone the dwelling. The line is still active. A new tenant has subsequently moved in, and if any calls or whatever are made I can and will be held responsible. I have tried to obtain some type of satisfaction, but all to no avail. What amazes me is the uninterested attitude, of this vendor.