no response to numerous attempts to cancel a landl

I have sent numerous emails and filled out the required forms for a land line to be cancelled, to which you only ever get an automated email response. I needed the line to be disconnected effective 31 March as tenants are moving into my property. I have called and been told you can no longer cancel a line with the customer care service centre via a phone call, but only writing! To which no one responds. I am beginning to think this is a ploy by Helkom to illicit more money from the customer and ignore attempts to cancel the service. This must be an infringement of my consumer rights.