Terrible Service recieved

I've sent a formal request to cancel my telkom line and ADSL in June 2017, The line was only cancelled after 3 additional complaints was logged with them and I received confirmation last month that my line is now cancelled but my account is still running up a bill.

I settled my account before cancelling but now I'm left with a bill which is long over the time of which I requested cancellation. I do not know what more to do as I have escalated the 3 complaints to get the relevant attention, but to no avail.... the level of incompetence of such a large corporation is shocking !