Misleading contract

I had a sim only deal contract with Telkom for 3 years and when my contract ended I called them to cancel my contract and they offered me another contract of which they 150 talk 'something '.The lady said they will give me R150 airtime and unlimited telkom minutes and she said it was month to month contract.I told the lady that I want them to use my main number when they load those minutes.Okay right come month end,the minutes were not loaded on my Sim card but money was deducted in my bank account. Out of anger,I reversed the amount that was deducted.I then called Telkom and they told me that I owe R178 and I paid the amount.On the 29 July 2025 I called Telkom again and they told I owe them R489,52 of which I know nothing about.Telkom say they loaded the minutes on my previous contract sim card and not on my main Sim card as we agreed. I have engaged with Telkom and they are not willing to help and they have sent my so called debt to their lawyers.I spoke to the lady called Kabelo Kokota and she said they can't help me and the only thing I can do is to open the case if i want the recording of the contract and she said the contract had unlimited data in it of which I was never told about.They actual did not tell me all the details about the contract. How do I owe so much after I had canceled the contract. I really need help.