Disappointed at MTN

Honestly I had a good relationship with MTN until they started *****ing money from my account, my contract had ended and I was advised by MTN's consultant to call in and close the contract if I am not upgrading and I did exactly that 3 days after the completion of my contract 2 months after my contract had ended and I had cancelled they were still taking money from my account. With the third ******** debit order I did a reversal and MTN suspended my number and they are telling me that I owe them, they stole my data and minutes that I had accumulated while I was still rightfully with them. How disappointing from such a big company that I had respected.