Listed on credit bureau because of Telkom's incompetence

I went to the Menlyn Telkom Direct store to cancel my Analogue line I had with Telkom back in April 2017. The consultant assisted me in store to get this done and after a week later she called to inform me that the line has been cancelled and I will not be getting billed anymore. To my surprise now when I app**** for a Home loan I got declined and I know my credit record has always been great. Upon further investigation I discovered that Telkom has listed me on the credit Bureau stating I owe R2881. How this came about I still have no idea as I was informed it has been cancelled successfully and my account was up to date at that time. I went to the same store again yesterday and I was told my account is Suspended and got another message from the Debt collectors stating that fact. This is the very pathetic service that made me cancel Telkom in the first place. Is this Telkom's modus operandi because I just discovered that this has been the case with so many customers. Telkom needs to sort this mess out and stop being such an inconvenience in our lives. I will be porting all my family's Telkom numbers to other networks, Telkom is pure pathetic with no shame.