Perpetually locked into a month-to-month contract with Telkom

I am on a month-to-month contract with Telkom and owing R2000 from the time the contract was active I assume. The sim card is currently suspended which I also e. assume is because of the outstanding debt. Despite the sim card being suspended I am getting billed every month. I asked why this is the case and I was advised that this is how their system works. They are in fact billing me for a service they are not providing in other words. So if I am unable to make repayments above the month to month contract I will effectively be indebted to Telkom for the rest of my lif