Telkom will not cancel my telephone lline!

Hi, I needed to get an adsl line for my studies, so I app**** on 13-02-2015 for my PREpaid land line to be converted to a contracted line with ADSL. Since the conversion my phone line was DEAD. The fault was reported multiple times, some of the references given were 177CRZ280213 and ***, I escalated the complaints on line but to no avail. On 28 March I gave up on Telkom and cancelled the line and was promised a credit as the line never worked. Cancellation ref AI***. (Ref Nokukhanye Ndwandwe ***9).No accounts were received and to my dismay I received a call this week that I am in arrears for R668 AND THIS FOR A LINE THAT NEVER WORKED, WAS CANCELLED+A CREDIT WAS PROMISED. I was asked to phone *** and speak to Yvonne. I tried for 3 days, but nobody picks up! Phoning 10210 is a waste of time, i listen for minutes on end to the commercials and over and over again I hear they are experiencing high call volumes. PLEASE HELP and Telkom, please can one of your friendly consultants sort this out?? They know me in your Northgate shop by now, but they say they cannot do anything as this is not their job!