Autopage suspends phone even after paying

My wife is with Autopage and yesterday her phone got suspended. After phoning them they informed her she needs to pay R106.10 for the month of October. So she says that cannot be as she paid the account in the beginning of October, so the next invoice should only be for the first of November. So how can you get billed twice a month? This is absolutely absurd and totally unacceptable. She should only have to pay the end of the month. Where does this amount come from? I told my wife to rather change from AutoPage to another company as this is not the first time it happened.