Harassment and abuse of consumer rights

My mother had a cellphone contract with Vodacom which expired in 2018. She decided not to renew her contract however, she has brought it to my attention again that the cellphone company continues to harass her for a monthly repayment of R700 for her expired contract to this date. My mother says the consultants from Vodacom have called and threatened her when she was ill and unable to make payments. Today Vodacom blocked both her and my brother’s cellphones, even after she made a payment of R400 in the last 2 weeks. She keeps enquiring why she is still paying for a contract that is no longer active, the consultants abuse and dismiss her questions. In fact the consultants told her that if she doesn’t pay, her phones will be blocked. Which is the case as of this morning. This cellphone company cannot be allowed to trample on consumer rights and ***** from the sickly. It has been 3 years since my mom’s contract expired, this is theft and a blatant disregard for consumer rights which needs to be corrected ASAP!!