Bad service ever from MTN SA

Mtn South Africa is the worst service provider I have ever used. I will have to close my contract with then ASAP. Their service is so bad. I will never encourage anyone is my circle to use MTN SA. I have finished paying my one contract in May month, however they are still deducting money in my account. Consultant says is my responsibility to call and advise them to close my line. Last month they even debited more that the expected amount.