Debiting after contract has ended!!!!

I am so dissapointed in MTN SA. Specifically the Westgate and Keywest branch. My mother is an elderly person, I went with her to both branches and even called them to inform that she doesn't wish to continue with her contact. They gave us confirmation that the contract wont be renewed however they continue to debit the full amount monthly. Taking advantage on people like that? Truly dissapointing.