Poor customer service

Telkom has debited more than what they should have supposed to from my bank account. I've been calling the call centre for several days now trying to get hold of their accounts department to reimburse the extra money that was taken. I've been told that they've logged the case and they will call me within 72 hours, which they've failed to do. I tried to follow up with the case myself and their stories change each time I call in, promising to call me back in 72 hours. Firstly its worrying that none of the call centre agents could account for the reason why so much money was taken in the first place , secondly they have made no effort in resolving this issue thus far which I believe is an urgent matter. I would like my money to be reimbursed asap and none of the agents could help me /or take through the right channels to retrieve my money.