Can't cancel the account

Have been trying to cancel our business account with Telkom since March 2020 as we moved premises. To date they have not responded and are still charging us every month. Have even requested a read receipt on the email I sent them and they have still not read the email. It's so sad as I am extremely happy with the service we get from them on our home line and with the LTE service we have for our daughter in PE. This makes me very wary to recommend them to anyone!