Telkom Month to Month contract ****

I had an a sim only data account with Telkom (24 months) which came to an end without skipping any payment. From there I was advised that the contract will adjust to a "month to month" contract which I was happy about, but the problem started when suddenly experiencing signal/ connection issues at home and I tried everything to resolve the issue but they failed which resulted me cancelling to contract. I called their call center and we did everything with the lady I was talking to cancel the contract unfortunately I did not take the "reference" didn't know that was important what i needed was to close that account because it was useless. To my suprise 7 months later I received a call from Telkom informing me that the account is still active and i owe them certain amount . my question what one need to do to cancel Telkom contract? I did not use their services because you blocked that sim card day of no payment, why Am I still owing you?