SIMO Telkom contract from hell

I took out a SIMO contract with them and continued the contract until it ended and necer renewed but now telkom keeps trying to debit R1533 from my account even though when I last made a payment the balance was R160 then one month later it spiked to R1500 and I have stopped paying ever since, my service has been terminated when I try to download my bill their online and WhatsApp system won't allow me. I tried canceling the debit but they keep using different accounts which make it hard to cancel as I was advised by my bank. I call the agent who are absolutely no help, when I called to cancel the contact to stop them from charging me for services I don't receive they kept moving me to different departments with each department saying that the department I'm coming from is meant to assist. Right now I have a negative balance every month of around R400 due to Telkom trying to debit me then charging me a R130 unpaid fee. They have terrible customer services with agents who lack adequate training on how to talk to disgruntled customers agents who also lack product knowledge. Right now I'm forced to pay a bill of R1500 which I don't understand how it got there because I had my spend limit capped at R50 but they insist it's additional charges I incurred for making calls. The statements they send out are very unclear in terms of how the money accumulated to what it is. I'm disheartened honestly because I'm unable to use my account and contemplating closing the account due to fear of being debited an amount I'm not sure of. What breaks my heart even more is the fact that I receive my grant money from the same account and each month I never get that money due to it being taken by overdraft charges and telkoms unpaid fee charge