Telkom debiting us after contract cancellation and notice period over

My husband has cancelled a contract with Telkom, given a one month's notice and then paid that up. He was subsequently billed DOUBLE after the contract ended and it bounced and now we are being harassed about legal action. This contract was long past it's end date, we gave notice, made payment, incurred UNNECCESARY debit order rejection fees and now these messages everyday. My husband has called and spoken to consultant's but they end up ghosting him or just not responding.

Is this how telkom does business??????

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