Continued billing after cancellation of contract

This is the comment that I placed on the Altech Netstar home page under their comments section, it is self explanatory:<br> On the 28th August 2015 I paid arrears plus costs of R560. At the time I spoke to one of the Credit Managers, unfortunately I lost her name, this after an extensive argument with one of your consultants in your credit department. I explained that the car was sold at the beginning of the year and that my daughter, Michaela, was in rehabilitation on KZN. She is still in the facility. The Credit Manager agreed that if I were to pay up the balance of the contract it would be cancelled, and I was given an amount of around R480, which I explained that as I am a pensioner I would only be able to pay a month later. This was accepted. I then received a notification via SMS that I owned an amount of R512.06 to settle the contract, the amount was settled on 28th September as arranged with the Credit Manager. I am now being harassed by Nu-Debt for a further amount of R70. As the contract was supposed to be cancelled as agreed with your Credit Manager I refuse to settle this amount of R70 as I have not been told what it is for. I threatened at the time that I would report Alt