Numbers that SSDA use for harassment

My MTN account was handed over to SSDA for non payment, although I have been paying MTN R700 per month for the lifetime of my contract. There was an issue on MTN's side where they did not allocate 15 my payments. But all payments have been allocated in November 2021. Since July 2021 I have been receiving at least 1 call daily from SSDA demanding payment. After I explain what the situation is and that they need to update their records, I get a SMS with a demand for payment. It seems like they are using the (072) 777-???? number range Numbers I have blocked already includes *** *** *** *** *** ***