Unfair Billing

I contacted Telkom to see if I qualified for a contact. To my surprise I was told I owe an unimaginable amount form a previous contract. I had a contract with Telkom for 24months. To my surprise I've been billed beyond this agreed timeframe because according to their customer service team "I did not cancel my subscription" therefore the services were still being rendered. All of this was unbeknownst to me as this was not explained to me while applying for the contract at the branch. I did not use any of the services a few months having subscribed to their services since I reported my phone as ******. Professional advise I believe having stated the former, would have been to suggest cancelling my contract. I now have a jaw dropping bill to pay which I believe is unfair ! I recently contacted Telkom and haven't received any feedback since. This lack of urgency in resolving customer disputes is blatant expression of Telkoms attitude.