contract dispute

Hallo,I cancelled contract a year ago because my phone was Rica barred and couldn't be fixed by autopage even though hundreds of rands and simswaps were done,they kept deducting from my bank even though I reported the problem for months,I had no service from them and couldn't use the phone.I was never in arrears got fed up and contacted consumer council who instructed me to cancel contract which I did.I mailed letter to them with consumer case number the works,now they keep harrasing me with debt collectors(the fourth company contacted and threatened me today)every time I have to fax proof of the letter with consumer case number to them.it's becoming humiliating and really irritating.please help me