Telkom has a poor service

Telkom debit money and not activity services and more than what we have agree. We have agreement of R 150.00 but they did not debit for two months as it was my fault and is not the first time when they do so. So I don't understand what the reason for switching of service I'd the debit before payment date and still switch off the service. When you call they say the business requirements say that they have to activate it after seven days which is wrong cos they still owe me half of what I have paid for.