Still got billed for Dial up after getting ADSL

I have a Surfmore10 charge of R67.0***l vat on my Telkom bill every month. I always thought it was part of my adsl internet package, but when I queried it at Telkom last month I found out that is was for Dial up internet I had before I switched over to ADSL internet connection. So basically for 4 plus years they have been billing me R67.0***l vat every month for Dial up internet I didn't know I still have, or ever used, or ever will use again, seeing that I have an ADSL line. So I logged a complaint 3 weeks ago with Telkom and demanded a refund on the service I didn't know about. Not getting any call or feedback about the complaint, after they told me they would phone me when it was resolved, I phoned them to find out why it is taking so long. They then just told me it was rejected and that I needed to cancel the service myself. First off I was never told to cancel the service myself when I switched to adsl. I assumed that by upgrading it will automatically be done. Why should I cancel an old internet service when upgrading to a new one and why was I never told. It just shows you how sly & greedy Telkom is by billing you for an old service even after upgrading to a new better one.