Account doesnt exist

So I cancel my line 2 years ago, I now get a phone call from a debt collection agency telling me I have been handed over by Telkom, I apologize and pay a promised amount, I then go to your store in Greebstone and was informed "you can cancel it online" I thought awesome! I go online register and Boom I get told " We could not identify you as a valid contact for this service account" so how the hell am I supposed to resubmit my cancellation if my account doesnt exist!?