MTN doesn’t cancel contrats

I had a cellphone contract with MTN for 24 months. I finished paying for it in December. I called in to cancel the contract, the lady that was assisting me on the 17th of December confirmed that the contract was cancelled. Only to find out no in January that MTN didn’t cancel my contract. They are going to charge me for the contract that they didn’t cancel. If I don’t pay for that particular contract they will block my numbers. I am very disappointed with MTN and how they now treat the customers. Once I finish to pay for all my contracts, I will never take a contract with MTN ever again. I have more than 10 years with MTN. But this is very disappointing. We are now getting ****med