Final invoice for service that was unused

Telkom is taking me for a one, I did a cancellation with Telkom in December with the aim of downgrading to a lower option of WiFi, Telkom took me from pillar to post about applying for a new product which is the one that I wanted to downgrade to, I waited for over 3 weeks and I decided to go to another ISP. Later after I selected with Afrihost Telkom has the nerve to send me a final statement with balance of R627 that I was expected to pay which I didn’t even use their services for that period, I was out of internet for about 3 weeks into 4 weeks. Right now my name is dragged by Telkom, my credit score went ****** down because of this ******* of a company! Telkom you better write this off and fix my name! You got no idea what is going to be coming your way, I’m very much prepared to do the worst!