MTN forcing us to keep contracts after it expired a YEAR AGO already!

We have been trying to cancel our contracts, which have already expired last year and July 2020, but to no avail. After phoning in, sending numerous emails and even visiting their stores, our contracts have still not been cancelled. Every single month they want to take a debit order and every single month we phone them and every single month they lock our lines due to non-payment. How are we suppose to cancel these contracts? At first we were told that we can only do it by phoning the retention department, which we did. Then we were informed to send a mail to their cancellations department, which we did as well. I have lost count on how m any mails, phone calls and visits we have made to MTN and yet again, our lines have been blocked for 14 days without getting it sorted. I would not recommend MTN to anyone. You just can not get rid of their contracts even a year after it has run out. Ridiculous to say the least!