Disgusted my MTN

I am very disgusted with MTN South Africa. I completed paying off my contract in April 2020 and canceled the contract in June 2020 after realizing that they are still deducting my account. I cancelled the contract. They blocked my number and i wasn't able to receive calls. I went back and forth with them for 2weeks not recieving calls and their Agents unable to unblock my number, later this issues was resolved. 1st of July they deducted my account again, now 1st of August they deduct my account again. What do i need to do to break away from this misery. I've been to their stores, logged calls but i am not getting any assistance. Does this mean when you take a contract with MTN it's a life time there is no way out??? Please help i am very annoyed by this treatment. I need the money they keep taking from my account.